Sonos to Amp - is simplicity better?

Unless your amp has an integrated DAC (like the Peachtree units, for example), the amp itself is irrelevant to your question. The Sonos Connect/Zone Player 90 has two methods of output: analog and digital. The digital outputs do no conversion. So if you output digital data from the Sonos it must be converted to analog before your amp can accept it.

If you use the analog outputs of the Sonos unit, the data has already been converted to analog by an integrated DAC chip in the Sonos. So your question is whether an external DAC will improve on the audio quality, compared to the embedded DAC module in the Sonos.

My opinion is yes, an external DAC will almost certainly improve the sound. I would advise you to test an external DAC and ascertain if you can hear a difference. But since the Sonos will only output at 44.1 kHz, there is no need to spend too much on a DAC. Also, you won't need a USB DAC - SPDIF or optical will do unless you want to complicate life and use an optical or SPDIF bridge.

I can speak to this with some experience. I have 6 Sonos zones in my home. My main system consists of a Sonos zone player driving a pair of Audio Note kits 300b Monoblocks directly (downstream from them is a horn system). I have tried, quite literally over a dozen DAC's in the 1k - 3k range. Every time I put the Sonos in directly, I feel that the sound is more direct, more honest, and more live sounding. It is a bit hard to believe I realize, but I have proven it to my own ears at least. If you by chance live near the Maryland / D.C. area, I would love the opportunity to show you just how good a Sonos zone player can sound driving high quality gear directly, with no preamp.

Martingren - I had a similar experience, just on a much smaller scale. I have a Sonos CONNECT and I was using the Emotiva XDA1 DAC to convert the signal. I did A/B testing between the Sonos internal DAC and the signal converted by the XPA1. At level matched volume, I A/Bd them for 30 minutes and could not hear any difference. The Sonos is a great piece of hardware in that it does all I ask of it AND it has no issues. The iPad interface is great. I would not ask for more.

OKAY, so, let's say the Sonos DAC is of acceptable quality and remove it from my question. Would adding a preamp in the path have any benefits? Drawbacks?

I'm building a new system for 2-channel, but already have 4 Sonos zones. I'll be trying this test myself, into a new preamp and direct into an amp. I'll try to remember to post my opinions here.

Without more information about the rest of your system, it's going to be impossible to tell if the rest of your system will be resolving enough to be able to tell the difference between using an internal or external DAC, or using a preamp.

My system consisted of an NAD C162 pre, Aragon 2004 amp, Emotiva XDA-1 DAC and several different speakers (Silverline Minuets, Dynaudio DM 2/6, Paradigm Studio 10s, System Audio 505s).

Using my very modest system as an example, I could definitely tell the difference between the Sonos internal DAC and the XDA-1. Using the XDA-1, the highs and lows were more extended. The bass was tighter, etc. Just about everything improved.

Still, if you like the internal DAC of the Sonos, the internal volume control of the Sonos could be a problem for you. It's volume control is within the digital domain, meaning that it cuts bits to control the volume level. At lower volume levels, the quality of the music may suffer.

Of course, beauty is in the eye of the beholder. I'd suggest that you try the Sonos straight to the amp. If you like the way it sounds, then you've answered your own question. I'll also tell you that when I've had to rig up something portable, I've often run a Sonos straight into an amp. I didn't think it sounded great, but it was certainly more than good enough.