What are the DAC specs of the Connect?

To start with, a Line-In signal goes through an ADC not a DAC. It would be digitised at the native rate of 16-bit/44.1kHz. More than adequate for vinyl.

As for connecting an external DAC, the digital outs are 24-bit/44.1kHz. However the 24-bit is only used to provide 'headroom' -- or more accurately 'tailroom' -- for the 16-bit content, so that the Sonos digital volume control can make up to approx -48dB of adjustment before any information starts to be truncated. The lowest byte populates as the volume is reduced from Full Scale.

Thanks and I take you're point about DAC A/DAC, I was paraphrasing. I think 16bit is fine but as to whether 44.1Khz is good enough for vinyl depends on the turntable. With that spec there is no benefit over a CD which is disappointing . . .

There never could be any benefit of vinyl over digital, unless of course you appreciate the ritual and the poor technical performance (tracking error distortion, SNR, wow & flutter, etc). Vinyl's dynamic range is generally held to be at best equivalent to 12-bit, and a typical frequency of response of up to 20kHz is encompassed by a 44.1k sampling rate

I think 16bit is fine but as to whether 44.1Khz is good enough for vinyl depends on the turntable. With that spec there is no benefit over a CD which is disappointing . . .
The link below is an educational read that focuses on debunking audiophile myths. See section 6 for a discussion on the audio quality of vinyl:

https://numeralnine.wordpress.com/2013/10/09/a-brief-guide-to-audio-for-the-skeptical-consumer/

You are of course free to disagree, but such disagreement would be based on faith, not science. And there's no arguing with faith.

The link below is an educational read that focuses on debunking audiophile myths. See section 6 for a discussion on the audio quality of vinyl:

https://numeralnine.wordpress.com/2013/10/09/a-brief-guide-to-audio-for-the-skeptical-consumer/
An excellent compendium. Archimago is also often a good read. I particularly enjoyed his analysis of what MQA is and what it isn't.

Again, thanks for your input on the ADC - In relation to sample rate, i was merely expressing a disappointment in the spec as significantly higher sample rates are available, In regards to facts, don;t believe everything you read. 'typically' and 'general' typically negate definition of 'fact'; there are lots of facts available thus - Vinyl goes well above 20k (up to 120K) and lower than most DA´s down to 5 hz.

But it can't take much dynamics in the highs so a vinyl mastering has very controlled highfreq dynamics. So there is no limited frequency range but limited dynamics...and consequently records have a smoother sound in the high range just because the cutting engineer needed to tame that high mid peaks to get a smooth cut.

Than you have resonances of the needle in the groove that actually work as a kind of subharmonic syntheziser in the 9 hz region.. so beside the noise and rumble it really makes the lowend fatter.. that together with the more controlled smoother highs..results in the often as better experienced sound of a vinyl release in comparison to its cd version..

highs reduce thru playtime..so the well used record dont goes up to 25 k anymore with its signal..but with its noise floor..
Thats also a problem for digitisation of old records..listen to them on the record the noise floor blend nice into the ultrasonics.. after AD conversions its bandlimited and appears more dominant. To do a real 100% transfer a of record into the digital domain you would need a dc coupled AD to properly capture the

Oh dear . . .

Fudjster - There is no way Sonos is going to meet your needs, you need to buy some really top end gear to get what you want.