DAC recommendation for an entry level system

I would like to add an apple TV a Logitech Squeezebox Touch and a Dune HD Prime 3.0 blu-ray player to my system which consist of NAD C375BEE Integrated amp, Rega P3 24 and Revel Concerta F12 speakers and would like to know if anyone can recommend a DAC. I have my music collection ripped to FLAC and Apple Lossless on my server. I can go up to $600 and I'm willing to buy used. TIA
For USB only I recommend the HRT Musicstreamer II+. I use this in my tubed system and it sounds wonderful.
Thanks for the recommendations. Ideally I would like a DAC that has Coaxial, Toslink and USB inputs. I'm considering the new Musical Fidelity V-90 DAC and also the Cambridge Audio DACMagic 100. The Maverick TubeMagic 2 DAC.
I head the Dac Magic with a Krell integrated and some Soinics speakers...really liked it. I've owned a PS Audio DLIII for many years and got a lot of enjoyment from it. Great build quality.
There is a lot to consider in the entry level market. Wyred 4 Sound uDAC, having one each of the inputs that you mentioned. There is also the Schiit Bifrost. The PS Audio DLIII is very nice, but if memory serves, it's a bit old and is limited by what it can handle 16/44.1 being the max.

I believe that the absolute best bang for the buck is the Emotiva. I have an XDA-1 that I've been using for a while now. It sounds pretty darned good and makes a good backbone for a digital system. It has two each of coax and toslink inputs, as well as USB and AES inputs.

The XDA-1 isn't available new, but they do have the XDA-2, which is pretty much the same thing, with some tweaks and analogue volume control (in case you want to use it as a pre amp too).

The XDA isn't the best sounding DAC out there, but it does sound good and gets you up and running with all of your gear. They're on sale right now for $340, I believe.

Once you have that, you can add more limited DACs that might sound better later.

My whole system is digital. I don't even use a CD player any longer. I'm running a Sonos, Squeezebox Touch, AppleTV and Blu Ray player, so it made sense for me.

Now I'm considering getting something "better" for my Touch, since that is my primary audio device.
Tony, what's the best (largest?) file you're able to pass from Spotify? Are you running it from the Squeezebox?
Mjmch2003, I've run Pandora, Spotify and MOG from all of my devices that support the services. Unless I'm mistaken, the highest bit rate that Spotify does is 256kps (if that high). As far as I know, MOG has the highest quality stream at 320kps for much of its content.

I don't know how else to answer your question. I may have missed what you are after.

The capabilities of the Emotiva DAC far exceed those needed by any streaming service. Just for reference, I've fed 24 bit, 192khz files through the Emotiva from my NAS, through the Touch, without problems. The DAC's performance with streaming services isn't really an issue.
I am using an older version of this, it sounds surprisingly good. The only thing well known that I've compared it to is a Wadia 121.... My Dac was richer, more organic with similar detail and sound stage.... But, what I have has an inferior USB decoder and I am using an Audio GD USB to Spdif. This is a very good value.

Thanks, Tony. I noticed that Spotify sounds better when I run it from my ipod through a Pure (transport) than if I run it off my Squeezebox. Same coax cable, etc. Have no idea why...

I don't doubt that at all. The Squeezebox is great as a sum of its parts, but it isn't the greatest at actually playing music. I've been tweaking my Squeezebox Touch for a while now and have been able to attain a higher degree of detail, wider sound stage and better bass.

A lot of the improvement in the Touch's sound quality has come from modifications that disable the wireless and the screen. If you have a Touch and are interested, look into Soundcheck's Squeezebox Toolbox (TT 3.0) and a third party app called "Enhanced Digital Out." Each has its own effect on the character of the music coming out of the Touch.
Micromega MyDAC: Asynchronous USB/Toslink/Coax 24-bit/192 Khz DAC for just $369. Check out the reviews linked from the "Reviews" tab. TAS was ecstatic about this unit.
Spotify does indeed stream at 320kbps, even through a Sonos system (as I am doing)