Sonos - Optical or Coax or RCA out?

To take advantage of the Nova's internal DAC (which some say is the best part of the Nova), you need to use a digital input. There is a general consensus that COAX -all things being equal- is better than Optical, but it may still depend on your source (computer based?). Did you consider USB?
Most often recommended length of digital COAX cable is 1.5 meters if you decide to go that route. There are many great cables out there, do a search on the topic.

You can connect the Peachtree directly to your PC via USB if proximity allows. If the Peachtree is setup in another area then the Sonos is a great product and I agree with Arni's suggestion of the coax cable interconnect.

This will be a nice setup but I feel MP3 will not do it justice. Try some lossless audio (16-bit/44.1 kHz) and you will hear a big improvement. Move up to 24-bit/96 kHz for an even bigger improvement (from your PC as Sonos does not support 24/96). Once you have listened to some high resolution audio you will really appreciate the Peachtree.

Whatever cable you choose will have less impact than your source material's resolution and bit rate.

Get a few different cables and compare. Coax usually sounds better, but there's an exception to every rule.

If contemplating optical, I bought a Sonicwave glass optical from Amazon for about $25 shipped. Sounds fantastic! For the money, it's easily worth the risk IMO. Just don't bend glass optical cables very much. You shouldn't sharply bend any cable, but glass is obviously more easy to damage.

Thanks for the feedback. My peachtree, computer and modem are all in different locations in the house. I have a NAS and I will have a zonebridge br100 on my modem and a zp90 in my peachtree. I hope to get the NAS setup to work. Are there any limitations with this setup that I should be aware of? Unfortunately, it sounds like USB is not possible.