Question

Connect no longer bit-perfect?


It looks like the Connect is no longer bit-perfect. Here's my evidence: let's discuss this.

First, I constructed a wav file of pink noise with amplitude ramping up from zero to digital max and back to zero.
I play this through my Connect and record the SPDIF output from the coax output into my PC.
The recording uses a Scarlett 8i6 audio interface set to use the Connect as master clock.
I record into a DAW (Sonar) multiple times - all instances are identical.
However, this recorded signal is not quite the same as the original wav file - it can be up to -21dB different.
See https://www.dropbox.com/s/t8od479xo9hi5el/connect_diff.PNG?dl=1
Note the expanded scale on the difference (third) track.

It looks like the difference gets larger when the signal is larger. To confirm this, I import the
original and difference files into Matlab and plot the raw data (difference vs original). There is clearly audio compression
happening here. See https://www.dropbox.com/s/p1yq6wcqafvnhaj/diff_vs_orig.png?dl=1
The scale is such that digital maximum is 1.

There also appears to be a slight bias when the waveform is negative and the signal is below the
compression threshold. See an expanded version of the previous plot
https://www.dropbox.com/s/9001tl9mkle4wly/diff_vs_orig_zoom.png?dl=1

Happy to answer questions about the method and conclusions.

Cheers, Peter.

p.s. Volume is set to fixed - I haven't tried variable.
In a loopback test (8i6 out from DAW to 8i6 in, no Sonos gear involved), I get bit-perfect cancellation.

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453 replies

which is why we have the output stream being mucked with. Sonos has not demonstrated they are serious about audiophile systems.
If you truly believe the latter part, sell the kit and move on if you are an "audiophile" and wish to remain so.

For other readers here, this might be of interest:

"Audiophile" is a very fuzzy word. One audiophile could find that the Connect is not worthy of being audiophile kit unless it was attached to an external DAC costing a lot of money. Another could find that even then, it is not worthy of being audiophile kit unless it was modified by changing its internal componentry - there are people that offer this service and audiophiles that buy it from them even today, at the cost of loss of reliability.

And some ex audiophiles - I was one for over a decade, dabbling around with heavy valve amplifiers, external DACs, expensive cables and monster speakers - find that a play 1 pair + Sub can beat any audiophile kit for sound quality at up to 2-3 times the price point of the former. With kit like the various play units, I find that the Connect is now obsolete from a features point of view - but not from that of sound quality.

Depending therefore on what kind of audiophile you are, Sonos kit is/isn't meant for you.
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I just noticed this thread and I can concur that there is something wrong
with the Connect. I have been streaming AIFF rips via itunes (from a NAS)
to an airport express, to an emotiva DAC via the optical output on the air
express. I've bee doing this for years.

I purchased a Sonos Connect a few weeks ago, with the idea that I would get
the improved user experience that Sonos advertises, but with the same audio
quality by streaming the same AIFF files to the Sonos then to the Emotiva
Dac via the optical output on the Sonos. Note that I have fixed volume
turned on, no EQ or cross fade.

The Emotiva Dac has two optical inputs, so it is easy to do an A/B
comparison.

The bottom line is that going through the air express is sounds far better
to me. The Sonos is less detailed, almost muddy. Not very pleasing at all.
It seems to me that the Sonos is transcoding along the path, which is quite
unexpected given what I have read.

Oh well, convenience matters and when I am in the mood to listen at more
then background volume, I can use the air express path.
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So much for my letter to the CEO, he quit. Followed the 100 laid off employees out the door, I guess.
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So much for my letter to the CEO, he quit. Followed the 100 laid off employees out the door, I guess.

No, he's remaining an employee

Give it a couple of weeks and send another mail to the new man
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Two letters and an email to Sonos about the issue that started this thread have gone unanswered. Four months ago, Sonos staff member, Ryan S. suggested that an option to allow a bit perfect stream was being considered. It's overdue and I'm tired of waiting.

It wasn't this thread that started me wondering why my music started sounding worse. I moved during October and November of 2015 and was remodeling for months. When I could finally listen to music, I thought maybe it was the smaller room or wallboard walls instead of the log ones in my house. I hung a quilt behind the sofa, moved things around and finally gave up and didn't listen to much music. Then I stumbled upon this thread.

I used the word "audiophile" in my first post and one member assumed I must be one of those that will spend $500 on a gold-plated wall socket and other such things. No, I mean audiophile in the ancient 1960s sense of wanting something better than a Zenith console to play my records. I have Peachtree Nova SE65, used Dynaudio Contour 1.8 MKII speakers and a used Oppo DV-981DH DVD/CD player. I sit myself in the sweet spot on my sofa, turn down the lights and do nothing but listen to the music. That's audiophile to me.

I used to rip my CDs with iTunes to Apple Lossless. Now I use dbPoweramp and clean up the tags with MP3TAG. I highly recommend both, not so much of a difference in quality, if any (the bit streams compare identical), but to better organize and maintain a collection.

I started searching around for a replacement that will do what the Sonos Connect was sold to me to do when I bought it in early 2015. I won't go into a sales pitch for what I found, but it is very important to say that the high-end audio store (Hanson Audio Video in Kettering, Ohio) where I bought the Connect was unaware of the change made in the November 2015 release. They, and all of the salespersons at the dealers I spoke with (Crutchfield, for example) were unaware and, concerned. To quote one, "We sell a lot of Sonos Connects as bit-perfect streamers."

A good friend recently bought a Connect based on my recommending it well over a year ago. He returned it and it trying a Yamaha WXC-50. I have decided to go with an Auralic Aeries Mini and a 240GB internal SSD drive I installed. I was no longer using the drive with my PC. No network except to tell the Aeries what to play. So far, so good. It is night and day better than the Sonos. Simply stunning. Clarity and bass bowled me over. I'll stop there, no audiophile terms.

I have a Sonos PlayBar for my TV in the great room (living, dining and kitchen combined) and will still use it for that and casual music listening (mostly Pandora) like house cleaning, cooking or parties. It’s plenty good enough for that. Sonos makes quality products, but it's obvious their priorities are not my priorities.

Your needs might be different, but I refer back to the post that started this thread. It is about users of the Connect that bought it to deliver a bit perfect stream. Most of us who bought it for that purpose don't care that it has a DAC and analog output. It that's not you, please don't flame me for agreeing with the first post, expecting a resolution and running out of patience.

As to the Connect DAC - before I boxed my legacy audiophile kit after buying Sonos, I did a lot of testing, admittedly imperfect, but good enough for my decision making. I compared the sound quality from analog output of the Connect with that from my SACD player, both into high end amplification and Kind of Blue was one of the test albums. I found no difference in quality and decided that I did not need the SACD player. Nor have I heard of anyone that has been able to pick out the Connect DAC in a well constructed level matched listening test against any other DAC - not even ones with five digit price tags. I therefore believe that the Connect DAC is audibly straight enough. As are many others - indeed I strongly suspect that a modern DAC is no longer a factor, having become a reliable commodity at a low price point.

Ironically, going by your findings, it would appear that those that don't think so, and want to use the Connect into another fancier looking external DAC may be ill served by Sonos while doing this, with audibly poorer sound quality than they would obtain via the analog outputs on the Connect!

Quoting myself here, in response to what may be happening with the Connect, because I doubt that any changes have occurred to the sound signature from the analog output of my Connect.
As another audiophile in the sense that I often listen to just music late at night, I have noticed no change in my sound since the time of the quoted tests. The last quoted sentence is a guess, no experience to back it up.
PS: And to highlight a word in the quote that may be skipped over - " level matched". If the signal voltage from the external DAC is higher than that from the Connect analog outputs by even a very small amount, it will be enough to have the amplifier set at the same volume control position to deliver sound levels that will be higher than more than 0.2 dB in comparison to when the analog outputs of the Connect are in use. Once that happens, all bets are off; a 0.2db level difference is all it takes for louder to sound better, including all the jargon that is used to describe better. There is a simple solution to this of course - the volume control on the amp needs to be set a little higher when using the analog outputs of the Connect to restore sound quality levels to that delivered by a DAC with a higher signal output voltage.
Hi Kumar

As far as I can tell, the analog output audio from the Connect is also compressed, with no option to turn this off.

Cheers, Peter.

p.s. Why AFAICT? When comparing the original wav file with the output of the digital outs, it is possible to exactly line up individual samples. It is more difficult to line up the original and analog output signals since the latter go through the additional DAC stage in the Connect, then an ADC stage to get back into my computer. Somewhere this screws up perfect alignment.
Peter, while that may well be the case, what matters to me is what my ears pick up to deliver the listening experience I obtain. Which has seen no change in 5 years of Connect use, so I tend to pass over this level of investigation and analysis, preferring to trust my ears.
Caveat: My ears are not made of gold but of lead and I get equally brilliant music now from my Connect Amp and 1 pair+ Sub equipped zones. So there is that.
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Kumar,

With 4,370 replies, I expected you would reply first. That's a boatload of forum time! I cleared said "Your needs might be different". Yours are, so why concern yourself with mine?

The simple solution would be to put it back where it was and let me continue to be satisfied using the DAC in my Peachtree amp, or choose the new enhancements they decided worked best in a Sonos environment. It's not unlike taking you car in for maintenance and being told the gas mileage will improve but the performance will be less because they decided to upgrade the car's firmware. Maybe it was bought because of the performance. Same idea. I bought the Connect to transport my files unmodified and now it doesn't. It doesn't matter if a majority of owners are satisfied, even thrilled. I've be hoodwinked!

DAC chips come with a fairly large number of settings that equipment manufacturers can make, so any one DAC can produce different output in different equipment. Your argument they are all pretty much the same conflicts with the chip manufacturers offering so many different settings. What could they be for other than changing the sound of the analog output?

If you are satisfied, good for you. I am not and nothing you say will convince me otherwise. You are saying how it SOUNDS, which is 100% subjective, I am unhappy with how it now WORKS, which is 100% objective. Transparent is what I want. I don't give a hoot about its DAC and analog output.


Yours are, so why concern yourself with mine?


Because it isn't just you that will read what I have to suggest, others read this forum as well, and some may well find it making sense to them.
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My position regarding the change Sonos Made to the Connect is crystal clear.

Kumar, I do not understand why you have even bothered to post in this thread. it's all about the Connect (not the Connect Amp, which you seem to have) no longer passing a bit perfect digital file and has zero to do with how well the analog output sounds to you on your Sonos speakers. It's irrelevant to the topic.

This is my last post on this thread. Because I still have a PlayBar, I might use the forum if I have questions regarding it.
Lol, good idea.

I believe that my post is relevant to this thread because regardless of what may have happened to it since 2011, my Connect which I also have, with its analog outputs in use to drive a third party amp + speakers, has caused no change in the way the music from my non Sonos speakers sounds. I agree that my post may not be relevant to those that are not concerned about how music sounds, but not everyone that is on this forum thinks that way, many of us are here to listen to the music without dissecting or otherwise parsing the equipment that delivers it.

On the other hand I also understand that those that want transparency for its sake, for that being the way they want the Connect to work, may want to change brands if Sonos does not restore it to them.
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Thank you for this thread. I recently started to notice that music on my active monitors, with my sonos connect as the source, seemed to have less dynamics than when I listened to the same tracks on headphones, with the analog out on my iPhone 6S as the source. But when I use CDs as the source instead, my monitors have a higher dynamic capability than my headphones. I searched around, and found this thread, which might explain why.

What to say: This is very annoying. It seems like such a simple thing for Sonos to fix. What do they lose by offering the possibility to stream bit perfect when in fixed mode? I would assume that most Connect users don't even use the fixed mode.

But my question: Is it correct that connect units that were manufactured befor 2011 should still be ok? I'm heavily invested in the sonos ecosystem, and love it very much, so would hate to let Sonos go because of this. But I've started to look into bluesound. So hoping Sonos comes out with a fix. Or I might try to find a connect unit from before 2011.
I would assume that most Connect users don't even use the fixed mode..

I'd have thought that they would, using the av/hi-fi amp to control the volume.

IIs it correct that connect units that were manufactured befor 2011 should still be ok? I'm heavily invested in the sonos ecosystem, and love it very much, so would hate to let Sonos go because of this. But I've started to look into bluesound. So hoping Sonos comes out with a fix. Or I might try to find a connect unit from before 2011.

Yes, I'd be interested in the definitive answer to this too, preferably from Sonos themselves.
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I would assume that most Connect users don't even use the fixed mode..

I'd have thought that they would, using the av/hi-fi amp to control the volume.

IIs it correct that connect units that were manufactured befor 2011 should still be ok? I'm heavily invested in the sonos ecosystem, and love it very much, so would hate to let Sonos go because of this. But I've started to look into bluesound. So hoping Sonos comes out with a fix. Or I might try to find a connect unit from before 2011.

Yes, I'd be interested in the definitive answer to this too, preferably from Sonos themselves.




I would second that and appreciate a response directly from Sonos.
If and when Sonos responds, I am curious to also know whether this matter has affected the working of Connect in all four modes: Fixed/Variable levels via Digital/Analog outputs.
I have seen no change in sound quality in Variable Analog output mode, and I have no comment on SQ changes if any via the other three modes, but it would be interesting to know the answer all the same.
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I agree, it would be interesting to get an answer from Sonos on this. Most of the folks here on the forum are enthusiasts, there is something about Connect being bit perfect that is pleasing, even if we can or can't hear a difference.
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I agree, it would be interesting to get an answer from Sonos on this. Most of the folks here on the forum are enthusiasts, there is something about Connect being bit perfect that is pleasing, even if we can or can't hear a difference.

As per my post above, I find the difference between the Sonos and AirExpress to be night and day. I continue to use the AirExpress for serious listening and the Sonos for casual listening. My spouse noticed the difference right away without me saying which input was which.
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I agree, it would be interesting to get an answer from Sonos on this. Most of the folks here on the forum are enthusiasts, there is something about Connect being bit perfect that is pleasing, even if we can or can't hear a difference.

Listening is tricky. If you know what you're listening for, you're likely to hear it. You might even hear it because you THINK it's there, even if it's not. But if you don't know what to listen for, you might miss it in a blind-test, even if it's there.

My subjective experience is that I hear a lower dynamic range on some recordings when I use the connect, compared to other sources. I don't hear it on typical studio recordings, pop, rock, etc. But I hear it in some classical and jazz recordings, where the dynamic range is typically much higher.

But again: Subjective listening is tricky. I won't swear that I would hear the same things in a blind-test. Now my listening has become biased because I "know" what to listen for. But what I think should be the goal, is just to provide good objective quality - especially if it doesn't cost anything. If the OP is correct here, the DSP Sonos applises actually loses 1 DB in dynamic range. That is quite a bit - 3 DB amounts to a doubling of volume. This is clearly within a range which is objectively audible, and for people like me who love their fair share of dynamic classical and jazz recordings, it's a bad thing. It's as simple as that, really. And it would be really, really easy to fix it. Seems like a no-brainer to me.
Seems like a no-brainer to me.
What we don't know is the reason/s why this was done; based on that, it may be that reverting isn't a no brainer. The other thing is that with Sonos focus is now on voice control, streaming services and allowing the use of Sonos speakers for other home automation tasks, the Connect is no longer a priority based on their target market assessment. Particularly if to fix something that, as Bob commented, causes a difference that can't be heard. I could be wrong, and only Sonos/time can tell.
Further to the above, the only Sonos statement on this thread on this change is to say:
"We are talking about a minor change to the audio when applying normalisation."
Now, while I have found no audible impact of this in my Connect that is working in variable analog output mode, I have to say that my one improvement wish from ALL Sonos units including play units is that normalisation works much better than what it does even now, and starts working on playlists made from different albums that are played in random shuffle.

Any drop in sound levels that is in excess of just 0.2 dB results in perceived degradation of sound quality, something that can come in the way of listening to music from such playlists, where sound level changes can at times be significantly more than 0.2dB. Along with changes in mastering quality, sound level changes from one album to the next caused at the time of mastering is what results in perceived and therefore distracting sound quality changes in the music being heard. Ironically, this is an issue brought to the fore because of the Sonos feature of easy to use playlists; in the past with CD players playing one disc at a time, one did not give a second thought to moving the volume control on the amp a little if necessary when a new CD started to play.

So it seems that while the change to bit perfect status has rubbed the bit perfect seekers the wrong way, it also hasn't truly addressed the normalisation issue that persists and raises its head in shuffled playlist play.

I have also found that sound levels from Apple Music are always a little lower than those when music is playing from my ripped CDs; easy enough to address when changing sources, but it means that mixed source playlists, played in shuffled mode, are not playable without often getting distracted by the sound level changes from one track to the next. Not an easy fix, I suspect, but one that would be widely useful. This may also be applicable for playlists made from two streaming services.

In my experience, the sound level changes are those that cause an audible degradation in sound quality, even when that isn't really the case as is seen when quality is restored once sound levels are accurately matched, while changes to bit perfect that may cause an objective change, do not do so to the extent that are audible, PROVIDED that all other things, including the all important sound levels to within a 0.2dB range, remains the same. And, as someone has pointed out, not knowing that bits are no longer perfect, helps!
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I will object to the statement that it 'can't be heard', though. If it is indeed a 1 DB adjustment in dynamic peaks, it is definitely audible. But then again: how much of a problem is this? What is audible and not audible is a tricky thing. In general, the human ear adapts to what we hear at any given time. Recent blind tests have for example shown that quite a lot of people now prefer low-quality 128 kbs MP3s over CD quality, because that's why they are used to from youtube. Does that mean that 128 kbs mp3 are "better" than CDs, or higher-quality MP3s like 320 kbs? Of course not. But people's preferences, and what may or may not be audible, can be a fickle guide to audio quality.

Therefore, I didn't notice this when the change came. The ear adapts. I only became aware of it when by accident I came to compare directly how some tracks with high dynamic content sounded on my headphones (the Sennheiser 650) and my active monitors when fed by the connect. The difference seemed quite substantial to me. After that, I started to read up, and became aware that the Connect was no longer bit perfect. By now it has biased my listening, and I tend to be aware of it all the time when listening to classical music, which I wasn't before.

Will it be audible to others? It depends.
- First, i haven't used the analog outputs on the connect, only the digital.
- Second, to hear this you need to listen to music with a large dynamic range. That excludes almost all the popular music that is produced today. Classical and some jazz recordings are still made with much dynamics though. It also becomes more audible if one listens to complete albums or compositions where there are both very loud and very low parts. Listening to mixed playlists will not reveal this to the same degree.
- Third, you need to have a system that is capable of reproducing large dynamics without clipping or distortion. When it comes to loudspeakers, that will probably mean either a rather expensive traditional hifi system, or some well-regarded active monitors from the pro world (the cheap JBL LSR 308 are excellent, and will get you a long way).

I would guess that this will not be audible to most people, as most people mainly listen to modern music where dynamics is limited. But for me, who listens a lot to classical and jazz and cares about the dynamic impact of recordings, it is both audible and important.
For what its worth, almost all my listening is to excellently recorded acoustic jazz, and my ears could not pick up any differences in a DBT back in 2011. I also do not think that the JBLs - and I have experience of the 305, as well as Adam active monitors - will add more resolving power than what my 1 pair + Sub does, based on my listening experiences.

As an aside, why do some think that Sonos, in its latest play units that use active tech and room response DSP, have not been able to do all that JBL has done in the LSR range? After all the LSRs are also cheap speakers, so those that deride Sonos because it is cheap ought to look down on the JBL as well!

Of course, as I have written earlier, I don't have golden ears in spite of having over a decade of exposure to high end HiFi kit. So, call me deaf, I have been told that often enough here for it to not matter.

I do notice a distinct and noticeable absence of anyone backing their claims for hearing differences that have sustained themselves in a well constructed and instrument level matched DBT though - of the kind that places like Hydrogen Audio deem necessary for instance - for the many subjective claims on sound quality that are made here as everywhere on the internet, which tend to let me think that I may be deaf, but I am not dumb:-).

And for those who think that Sonos, that makes the current model 5 units, and also a set up with the sound quality of a well placed 1 pair + Sub, both of which can further be room response optimised with Trueplay, does not make serious HiFi kit only because the Connect isn't bit perfect, there is little to be said. Those with the conviction behind this thinking will sell their Sonos kit and move on, and good luck to them! My choice for quality sound now is room response optimised play units/Sub for home audio, over worrying about things like bit perfect which isn't something my ears are able to hear anyway. I also no longer bother about, for example, what kind of power supply module delivers the best "quality" power for getting the best sound quality; something that I admittedly also dabbled with in my audiophile days. PSUs, DACs, ICs are now all cheap commodity componentry, and I trust Sonos to have done all the hard work in choosing what delivers the best sound for the price point, which finally is all I am interested in, because the days of being an equipment hobbyist are behind me. It took a couple of serious tests at home when I still had my high end kit to realise that it wasn't necessary to remain a hobbyist to obtain music of excellent quality at home via Sonos. A significant reduction in both the investment as well as footprint reduction and cable clutter elimination was a very welcome by product, but not a driver of the change.

I remain curious to have a Sonos response to this subject of course, but for the normalisation subject that is far more important to me from a consistent sound quality perspective, I have opened a new thread.
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Interesting comment, Kumar. I'm a very rational-minded audiophile, and have never bought into the thing about magic cables or power conditioners. But there are substantial and audible differences between speakers, speaker drivers and speaker technologies. This is also something that can easily be shown in measurements as well.

The thing is: I don't trust listening tests. I don't trust sighted listening (when we know what gear we're listening to), but I don't trust simple blind tests either. It is very easy to get negative results even when there are in fact objective difference that can be audible. Here's a thread on that on that on another audio forum: http://www.audiosciencereview.com/forum/index.php?threads/limitations-of-blind-testing-procedures.1254/
In your case, for example, your listening to Sonos will be biased by the fact that you think they make excellent products, and by your conviction that traditional audiophoolery is a waste of money and that sonos is just as good. Others will be biased in their listening by the very opposite convictions.

And I agree that sonos makes excellent gear. A pair of play:1s together with a sub will easily outplay most traditional passive systems in the price range (my subjective opinion is that two play:1 + sub is a better-sounding option than a pair of the new play:5s). But the JBL 305/308s, for example, are superior. When I say that, it is not only based on my own listening. After all, your listening experiences may be different from mine. When I say that, it is based on objective parameters that have been shown to correlate with listener satisfaction in psychoacoustic studies: Frequency response, dispersion pattern, polar response, response in the time domain, the ability to play loud without distortion, etc. On all of these parameters, the JBL 305s/308s perform better than a pair of Sonos play:1 with sub.

But two play:1s with sub does sound very good. Not just "good for the price", it sounds good. But this was a detour, though. The point is there are measurable differences in audio quality. At what point these differences become marginal, that's something one can discuss. But the differences are there. To limit dynamic range IS something that affects objective audio quality in a negative way, and it is within the range we KNOW to be objectively audible. How important this is to us subjectively, is - well - a subjective thing. I really can't see why we can't just leave it at that.

Therefore, I didn't notice this when the change came. The ear adapts. I only became aware of it when by accident I came to compare directly how some tracks with high dynamic content sounded on my headphones (the Sennheiser 650) and my active monitors when fed by the connect. The difference seemed quite substantial to me. After that, I started to read up, and became aware that the Connect was no longer bit perfect. By now it has biased my listening, and I tend to be aware of it all the time when listening to classical music, which I wasn't before.

These words beg two questions:
1. Why is not possible that the same difference would have been heard - between the headphones and the active speakers - before the change? I realise that this isn't a question that can be easily answered, but it remains a valid one even so. And as I am sure you know, it is very difficult to obtain the same sound quality that a good headphone can deliver, from speakers that have to overcome all the challenges of room responses and ambient noise levels even in a very quiet room. The closest comparison can only come from a speaker set up that is optimised for near field listening, but even that is disadvantaged compared to quality headphones. Comparing sound quality between headphones and speakers is apples v oranges.
2. And to complete your own line of thinking in the second part - why can't it be said that what you are now aware of is just the result of Expectation Bias and not any change in the Connect?