https://www.google.co.uk/amp/s/www.techhive.com/article/3546333/sonos-port-review.amp.html
 

Updated Port review on Techhive. Now with input from Sonos. Apparently the Port does process the sound differently from the Connect via Digital Out. 

The DSP, according to this source, is designed to adjust for “the different characteristics iof] different recorded content… that impact volume output. The DSP helps to keep it balanced so that it protects the listener’s equipment and ears.”

The workaround is to use the ‘fixed’ output. This may explain why I’m hearing it using variable & others aren’t if they are using fixed. It also explains why I was happy with the Sound from the Port when so switched to ‘fixed’ mode. 

I am not sure how credible this attribute is, including the claim that Sonos have owned up to it. 

What is also strange is the claim that this issue arises only where the digital outputs are concerned, and is not there with analog outputs where the differences between Connect and Port are said to vanish.

Why Sonos would mess around with digital outputs but leave analog outputs untouched is a mystery.

A thought-provoking review. Its findings to a degree chime with my observations of soft-knee limiting in Variable Volume mode above about 85% (flat EQ) on the digital out when the input samples were at Full Scale. Soft-knee limiting is common, in order to avoid hard clipping in signals which could otherwise be driven above Full Scale by EQ etc. It could also mitigate potential inter-sample peaks over FS in a downstream DAC.

Fixed Volume is flat, without EQ, so a limiter isn’t strictly necessary. The digital signal can be passed straight through from the decoder. 

The observation about the analog outs is interesting, and on reflection makes sense. Whereas the digital outs have to be protected against going above Full Scale by a soft-knee limiter there is no such hard ceiling for the analog outs. Internally the pipeline is evidently 32-bit, so in both the digital and analog domains there is no practical limit anywhere. 

Will this limiting come into play where the EQ is set to flat, for digital outputs in variable volume mode? And even if that is so, does it come into play only when the volume slider goes past 85% ish? If so, this will not be heard if the Port unit is at say 70% volume with the downstream amp delivering more gain to compensate?

Is this limiting the same as was supposed to have been done in Connects some years ago?

I think the reviewer was implying that this limiting seems to be more aggressive in the Port. That would echo my own findings. Particularly with it making streams from 6 music sound almost the same as a Tidal or Apple Music stream.

What audiophile uses an external DAC with the variable volume setting?

Ironically, and having extensively used a USD 2000 external DAC in the past that weighed more than most amps, all of this seems to say that one may as well use the Connect and Port via their analog outputs. I have not found any differences employing said DAC or that in a high end Marantz SACD player, compared to analog outs from my two 2011 make Connects, back in the day when I was evaluating them/Sonos as a replacement for these bits of “HiFi” kit.

Sources ranged from lossless CD rips as well as iTunes lossy AAC downloads, and speakers ranged from Harbeths to Quads, with high powered Quad amplification a constant. The Connect did the job just as well, for much less, offering a lot more convenience via playlists, and access to a lot more music.

And today, Echo Show units wired to line in jacks on Connect/Connect Amps do just as well, sourcing lossless transcoded CD rips from a local NAS on a Raspberry and from Amazon/Apple Music.

One that needs the volume control on the Sonos app to work?

But, as I have said in another post that has just been red flagged although it endorses Sonos quality, my experience suggests dumping external DACs, and using Connect analog outputs, using EQ to accommodate any room acoustics or speaker placement issues - in which case this fixed v variable thing is moot.

My question was rhetorical.  I just find it strange that audiophile circles who  preach bit-perfect would immediate switch it off for convenience.  Also, I mention in another thread that a reviewer negated all objective testing when they switched off Fixed volume to fiddle with the equalizer.  In addition to the subtle effects stated above, Variable volume means volume matching now comes into play, and we all know how that affects objective listening.

I know; but my reply was for the benefit of others, who may not see that the word audiophile covers a wide range of behaviours, not all of which are extreme -  extreme like some that will disdain EQ or Tone controls because these “corrupt” the purity of their signal, not realising that these are needed to compensate to some extent for the mess that their rooms make of the sound heard when poorly placed speakers interact with the room acoustics to make a hash of the sound delivered from these speakers even when fed their “uncorrupted” signals.

All well and good, except a subjective reviewer should specifically mention these factors, thus removing anything definitive about their review.  But we all know pigs will fly before that happens.

That’s what appears to happen. The limiting gradually increases as the volume setting heads towards 100%.

The behaviour I witnessed -- albeit with single-frequency test tones -- suggested it started to cut in above about 85%. Whether it has the effect of compressing the dynamics lower down the volume scale I can’t confirm objectively, but that seems to be what some people are saying. 

Similar I guess. The fault in certain Connects was that the limiter was being applied in Fixed Volume too. 

Why then is this not done for Fixed volume digital outputs? Is Variable volume at 100% with flat EQ not the exact equivalent of Fixed volume? Or is it done assuming that EQ will be used in the former case even when it is not actually being used?

Fixed is a straight transfer from the decoder, bit-perfect. Variable runs the risk that EQ could push samples above Full Scale and hence into clipping.

In the old days of ZP80 it was assumed -- and proven if I recall -- that Variable/100%/flat-EQ was identical to Fixed, i.e. bit perfect. If EQ ran the risk of pushing the signal into clipping it must have been defeated in a progressive and gentle fashion.

Based on the Sonos comments in the TechHive review it sounds like they took a different design approach with Port, possibly driven in substantial part by the needs of the installer community. On the face of it Variable is geared more towards their needs and Fixed to audiophiles. 

I have to say, your tone is very antagonistic. I am not & have never claimed to be an audiophile. I simply stated that the Port sounded more compressed & less dynamic than my old connect whilst using variable output. As I’d paid £280 to ‘upgrade’ this bit of kit I was suitably miffed! Now as it turns out I was completely correct & the sound is being ‘managed’ more aggressively via the digital out. Something that only a few posts ago you were saying was not possible.

And to whose needs are the analog outputs geared to?:-)) I know they work fine for me...

Have you tried using the analog out with Variable volume? According to that article the DSP limiting/compression only applies to the digital out, which in retrospect is logical.

I have Ratty, thanks for asking. I think I said ‘much’ earlier on in the thread that the differences between the analogue outs on both units were minimal. I’d definitely say the Port had a little more clarity than the connect in that respect. However it still doesn’t sound as good (to my ears) as the connect through the Rdac. As I’ve managed to achieve what I wanted to do at the beginning of this thread( which is continue to use my hifi as part of an S2 set up) & only having to splash out £199 in the end I’m quite happy! Sonos also allowed me to carry over my 30% discount after returning the port too. So all in all it’s been a loooong road but it had a happy ending!! 

Yes, apologies. I just looked back over the thread and noticed your comments about the analog out.

I’m wary of confirmation bias, but having removed the DAC from the path between my Port and a Schiit head amp I suspect my Senny HD650s may be sounding a tad more ‘dynamic’. I’d had to use variable volume on the digital out on account of ergonomics and occasional EQ tweaks. Time will tell I guess...

Please provide a link to where I said it was not possible. I’ll be waiting . . .

Also, one must be wary using the variable output, for unmatched volume levels can account for “differences” heard between two audio samples as much as actual differences.  Matter of fact, the bias for volume is so subtle (yet strong), it can be shown to be present even when the most listeners cannot distinguish a change in volume (usually between 3-5 dB change). Of course, a properly level matched ABX test will shine far more light on what is at work here, but I’ve yet see one, either in the audio press, or here.

• jgatie

• 10 days ago

How are they supposed to “update” something that is already bit-perfect to the source?  
 

See above. Ok I’m paraphrasing! Maybe even mis quoting!! Clearly it is not ‘bit perfect’ though. Nor do I care. If it sounds good! Unfortunately it doesn’t. 
The implication was that the Port was putting out an un processed digital signal. It isn’t in variable mode. I don’t want to get in a fight about it. 

Also, I don’t need to do a level matched A/B test. The differences are not ‘subtle’ enough to be a mis match of volume. 
I’m not disputing that confirmation bias is not a real phenomenon. Just that I really don’t think this is a case of that & Sonos have pretty much come out & said as much.

Neither link goes anywhere except to the top of this page.  InSided sucks.  But I’ll take your “paraphrasing” comment as an admission that I never said it was impossible (because I know I didn’t).   

As to your quote - At fixed output, it is most certainly bit-perfect.  If you were talking about variable output, well then by definition it is not bit-perfect, and thus is open to all sorts of updates.  I apologize for assuming you were speaking about fixed output, as I have repeatedly said in this and other threads that the Variable setting tosses all definitive,objective comparisons out the window.  Why you would think I was talking about an output that is by very definition not bit-perfect when I mentioned something being bit-perfect is puzzling.  

The quote was yours about it being bit perfect. I just don’t don’t know how to link back to it, so I just copy & pasted it! Sorry! Yes it was a misquote. For that I apologise. 
My point was that you jumped in to say that I must be wrong without reading the thread fully. No offence taken. I assumed that you had read the thread & knew that I was using ‘variable’. 

I never once said you were wrong.  I asked a question, assuming (wrongly) that you were talking about Fixed volume (hence the bit-perfect reference), since Fixed volume is the only objective way to make a comparison.  If you had answered “I wasn’t using Fixed volume, so I’m not talking about bit-perfect”, I would have said “Oh, sorry for assuming. Yeah, that can definitely be different”