It depends what you mean by “solely as an amplifier”. There is no analog path through the Amp.

Line-In signals are digitised on receipt, handled internally digitally, then converted back to analog to drive the speakers. With an Uncompressed setting this digital path will however be lossless. If there were to be any audio imperfections introduced these would be totally insignificant compared to those inherent in the original turntable signal.

Note that an Amp will require the turntable to have a phono pre-amp, either built-in or separate.

@ratty thank for the reply.

That pretty much rules out the AMP then. I will probably just go with a Sonos Port instead. If not just keeping my Turntable setup in its current autonomous setup.

The Port only lacks amplification, but in all other respects works just the way the Sonos Amp does. 

By using the Sonos Amp what do you think you will lose out on?

That was a rhetorical question; you will not lose out on anything on heard sound quality and gain the benefit of the Dali speakers being able to play streamed music independently or grouped with other Sonos speakers. 

But the best way to satisfy yourself is via a test if you can get the Amp on a returnable basis.

@Kumar  I have an idea (maybe im crazy) that the AD DA conversions ruins the whole idea of using a turntable. Why not just go with lossless streaming instead.

Its like eating a burger with a veggie beef. It tastes fine but you just know its wrong… (again maybe im crazy).

Vinyl, flawed medium that it is, has already adulterated the sound to such a degree that an AD/DA would make no difference. 

There is no sound quality reason to go with vinyl.

Two valid reasons are if you have a large collection of rare vinyl, not available on Spotify, for example.

The other reason is for the fun of it.

By staying away from Amp you are depriving yourself of the real benefits it can provide in enabling easier play of all sources on all speakers. In addition, you have a smaller footprint than the NAD, and you can leave the Amp on 24/7, where it will auto sense the line in signal from the turntable.

Actually if one looks at all that is involved in the making, and even more in the playing, of vinyl, I would say that it is a minor miracle that it can sound as good as it can when the turntable is properly set up.

Im not trying to imply that vinyl quality is better than digital lossless. I was just asking if the Sonos AMP would be in line with the whole analog setup idea. Which it isnt…

Objectively, why does it matter?

You could also try the Amp and trust your ears: if you do not like how the Amp sounds (caused by the digital signal route or not) , send it back.

Purism takes many forms...

Loss of quality in the ADC/DAC/ADC signal chain is a myth.  Nyquist/Shannon states that for a band limited signal like audio, the analog signal going in is exactly the same as the analog signal coming out.  Not approximately, not close to the original, but exactly the same with no loss of signal at all.

That is what I suggested as well; and such testing can also confirm that all the nasty vinyl crackles and pops are accurately passed on to the speakers as before, as well as any desired vinyl distortion/warmth because the conversion process will not hold back any of the aforesaid.