External DAC with Connect

the sound is much better. I firmly believe that better DACs make for better sound. I have no scientific data to back this up - just my ears. By the way, I agree with you that speaker placement is important.
If it sounds better to you, that's fine. Perhaps it will, perhaps it won't to me - but that is hypothetical and irrelevant.
Consider this though - even a 0.2 db increase in the sound level, needing to be measured by instruments to be eliminated in a controlled blind test, can make the music sound better to any human ear. It is an old trick that every good stereo salesman knows.
I am not saying that this applies in your case, but it is possible that signal level voltage/input sensitivity differences could be causing these in your system with no change in the volume control knob setting.
And better DACs will make for better sound, provided that if you are using the word "better" with reference to instrument measured output parameters, these improvements are within the threshold of normal human hearing. My experiences lead me to think that good enough - in the sense I refer to - is reached quite low down the price point with the resolution of the issues that plagued early days DACs now widely known, and not expensive to eliminate using mass manufacturing state of the art tech.
In digital audio spending more money will get you lots of things - but not, beyond a point quickly reached - better sound quality that your ears will convey to your brain, if you deny your brain every input other than the one conveyed to it by them.
Given that your ears may be better than mine, in your case that point may be higher than mine, but not by a whole lot, I suggest.
Bottom line - if your system sounds great to you, wonderful. It doesn't however flow from this that those who can't hear the sound improvements from a better DAC are Luddites or worse.
A thought experiment for you - if you were to do the sound level matching to less than a 0.2 db difference, and the Connect was to sell for USD 2000, would you think different?

Hi Kumar - Good points. My ears tell me that the higher quality DAC sounds better. When comparing the Naim unit with my EMM Labs unit, there is a distinct improvement in the presentation of music - I guess you would call it the soundstage. Musical information just seems to open up. I could talk about air around instruments and blah, blah, blah, but that would just make me look like an audiophool, as one poster has put it, and I'd like to think that I'm not a fool. Would I think any different with regard to the Sonos Connect if it cost $2000? Well, if allowed to demo it in my system, comparing it to my other DACs, and if nothing else changed, I would still likely come to the conclusion that its DAC is not as good as the others, surprising given the price. I understand your point. Just because it's expensive doesn't necessarily make it a better product. I've been around a lot of high-end gear over the years and have reached that conclusion long ago. However, having said that, I still think that as a rule, you get what you pay for.

there is a distinct improvement in the presentation of music - I guess you would call it the soundstage. Musical information just seems to open up. I could talk about air around instruments and blah, blah, blah, but that would just make me look like an audiophool, as one poster has put it, and I'd like to think that I'm not a fool.

However, having said that, I still think that as a rule, you get what you pay for.
The things you describe is exactly what is universally heard when sound levels rise by as little as 0.2 db, unless they were at very loud levels to start with. And exactly the same things are heard to collapse when the sound level drops. It is universal and nothing to do with being a fool.

What comes in the way of getting what you pay for in terms of heard sound quality in this case are the two very different scales at which the speciality hifi audio companies operate compared to volume players like Sonos and many others. For the former all costs per unit are higher, as is the need for a higher per unit profit to sustain the business. That translates to a higher selling price for essentially the same product. For this they may throw in a better looking cabinet, more features, better hardware service years into the life of the equipment - but they can't extract better sound from the commonly used electronic designs and componentry, once some minimum standards are met in this area. This has been true of amplifiers for decades now, while the DAC side of things have evolved to a similar level much more recently.
Different rules apply for speakers, where the rule applies much more because getting/making better components such as cones, tweeters, enclosures, and the other mechanical things a speaker incorporates can be more expensive. Which isn't to say that there aren't any lousy expensive speakers. Or the vice versa. But this tends to be an exception.

I am with Kumar here. I have a Benchmark DAC (with pre-amp) between the Sonos and the McIntosh power amp and Thiel speakers. It sounds great but when I tried it without the DAC the difference was minimal and certainly not worse.

I am with Kumar here.
All amplifiers that have a instrument measured flat response and are working within their design limits, do not have a sonic signature under controlled testing, i.e.,they sound the same. For the flatness to be such this is true to the extent even the best of human hearing can notice that it is not, is a problem that has been solved decades ago. The sonic signature that is heard is because of sound level differences, or because speaker behaviour in terms of demand for power is driving the amplifier to beyond the design limits where the delivered response is flat.
My listening, some reading about digital audio and common sense tells me that the same stage has also been reached by now for thing such as CDPs, DACs and streaming boxes such as Sonos. I would however still not make as categorical a statement about these as I can about amps. Can anyone else here, based on more knowledge/experience? The parameters for the relevant flatness would be different than for an amp, but the concept should be similar. It should actually be easier, because the X factor of speaker power draw will not apply here.
This of course does not mean that USD 70k DACs won't be promoted.
And while a USD 100k speaker may well have the power needs that only a USD 50k amp can fulfil, there is nothing that I can understand will be different on the input side of that amp that will need a USD 70k DAC. I know I would still struggle to hear the difference between that one and a Connect wired to the analog inputs of the same amp. But it would be interesting to know what kind of measurements/thresholds one would look for in a CDP or a audiophile Connect, for it to be good enough in terms of not having an audible sonic signature to the most acute listening for such a system, provided of course that nothing but the ears are in play. And the sound levels are level matched by instruments.

And while a USD 100k speaker may well have the power needs that only a USD 50k amp can fulfil, there is nothing that I can understand will be different on the input side of that amp that will need a USD 70k DAC.
Thinking a little more on these lines - I don't know of any 2 channel speaker in the world that needs more than 1000 watts of clean power from the amplifier. But I do know of a few solid state amps that can deliver this, and they don't cost more than USD10k.
Imagine a system of USD 100k speakers, USD 10k amp of 1000wpc, and the Connect wired to its analog inputs, playing lossless files. Using commodity speaker cables of adequate gauge, and good enough interconnects from the Connect to the Amp - the entire cable part of the system available for USD 200.
A level matched AB test of this system with another costing USD 200k using the same speakers - the money being spent on amplification, DAC and fancy cables that don't have inbuilt sonic signatures - would be revealing were any one to carry it out. Saying anything more would be speculation.

My listening, some reading about digital audio and common sense tells me that the same stage has also been reached by now for thing such as CDPs, DACs and streaming boxes such as Sonos. I would however still not make as categorical a statement about these as I can about amps.

When I compared the Sonos's own DAC with my Benchmark DAC1 HDR, all other things being equal I did hear a difference (or at least I thought I did). The Sonos sounded a bit "warmer". In view of all the other parameters that influence our perception of sound, like the recording quality, acoustics of the room etc. I would not lose any sleep over minute perceived differences.

As to amps, Kumar said it all, although I do wonder how loud he plays his music ... 1000 watt is a lot of "spare room" considering that the volume in a living room (at least our living room) rarely gets above 80 Db and a few watts.

I do wonder how loud he plays his music ... 1000 watt is a lot of "spare room" considering that the volume in a living room (at least our living room) rarely gets above 80 Db and a few watts.
I don't need or have a 1000w amp:), I only referred to it as an example of the most power that any home audio speaker in the world will need!
My music listening is also at moderate to low levels, no head banging stuff.

Where the very large majority of modern amps are concerned, all that is needed from a matching/SQ perspective is whether it has adequate power to drive the speaker in question with some power in reserve - if that is the case, it won't have a sonic signature so one can choose based on things like reliability, features and after sales support.

What will be very useful is to have a similar specification parameter for a modern day DAC, such that if that is met/bettered, the same will hold good for it. And use that parameter/s to assess the Connect.

Beyond that differences may exist, but if they can't be heard in a controlled test, they are irrelevant.

In the search for the ultimate quality of sound (?) surely the most significant factors in the quality are at the beginning and the end of the chain.

Microphones and their placement.
The handling/ amplification of low level signals from the microphone...
The transformation of electrical signals back into acoustic energy.
The listening area/ position etc.

My own experience has been that themove from Amplifiers via Crossovers, to active speakers where the drive units are closely coupled to the integral amps has made the greatest difference so far. Actually coupling a loudspeaker unit to generate air pressure changes is probably the hardest part, and probably the place where the amateur has most choice.

Changing my passive speakers to actives has made the most difference in my listening experience when listening to excellent minimally processed recordings. I have found it particularly revealing on Hyperion recordings for example, with acoustic instruments, human voice and also piano (quite often badly recorded). I know what these sounds should sound like from the concerts we attend.

I dont really know what non acoustic instruments are supposed to sound like so i cant really tell.

None of this is science, only true double blind testing can really determine if there is an actual difference that can be heard. If there is then do the science and determine what parameter or factor produces that change.

Too many of the current hifi mags just rather sloppily say X is better than Y but dont bother to measure why. I guess its hard for a magazine that relies on advertising to go that extra mile and prove the £5000 amplifier is no better than a £500 amplifier, its not in their commercial interest!

Its only an opinion of mine with little science and no measurements to back this up, but the electronics is probably now as good as it needs to be if competently designed. Try actives and get those pesky drive units doing what they should do!

Oh well off to buy a £500 mains lead and a mains conditioner for my £5 Tesco toaster so i get a much better uniform browning of my toast.....