AppleTV work with USB DAC?

Can an AppleTV modified via some software to enable and use
its USB Port to output digital audio to an external USB-DAC?

I've been searching the internet for this answer. I know the
MacMini will allow this but I like the "fanless" AppleTV for
quietness and small size.

AppleTV can be "hacked" to enable USB output, but I believe it's more than software changes. I use my AppleTV with a VH Optocoupler II toslink cable to a Peachtree Nova Sabre Dac, and that is extremely good. If your DAC is USB input only, my suggestion is of no use..of course.
Don't think it can be done. BTW, the ATV does have a fan, when you pull the plug you can hear it spool down. I currently have an ATV connected through optical to a Theta TLC and then to a DAC and am happy with the sound. My main issue with the ATV is it very frequently hangs up and needs to be restarted, in particular after getting the new version of Front Row. Thinking of the Mini but it doesn't sync the same way as the ATV to use the Remote and has HDMI/component so video out is pretty straight forward. Now if I could only get a combination of the two.
Don't think a USB DAC can be used on Apple TV. I've used the ATV with excellent results thru a Benchmark DAC1. Unless you are up to doing serious mods, it's probably best to use optical out.

***On a side note, I read in a forum about a couple audiophiles who built a capacitor filter fob that plugged into the USB plug and added additional filtering to the 5v line. Apparently both the toslink transmitter and usb share the line so the extra capacitance on the 5v line contributed to better sound out of the toslink output. Basically it looked like a thumbdrive, but contained capacitors instead and only used the 5v line, not the signal lines.
When using the Apple TV, is there any way to select songs and playlists remotely via computer rather than the TV screen? Or is the ATV inseparable from the TV?
This is the only way I know of to set up your ATV for use with the USB external hard drive capabilities.
Mingles- using an Ipod Touch or IPhone you simply use Apple Remote to run the music, and it's a beautiful and simple interface. And the Apple Remote app is free as well.
Wow the AppleTV has a fan? I didn't know that. I only saw
it at the Apple store and I really liked the small size and
of course the killer GUI.

I was reading that the AppleTV can be hacked to the point
where you could install a full version of OS X. Somehow
I was figuring if the USB could be enabled for USB harddisks
then the next step would be to copy over Audio Midi Setup,
start it up, and then select the USB port for Audio output.

Gherrera1: I will have to check into that capacitor mod
on the AppleTV. We emailed a year ago when I bought my
Krell 400xi and SACD3. You were considering the AppleTV
or MacMini back then.. I guess you picked the AppleTV..

Has anyone tested various glass Toslink cables to find
out which one sounds best with the AppleTV ?? The 3
Toslink cables mentioned often seem to be:

Van Den Hul Optocoupler
Wireworld Super Nova 5
AudioQuest Optilink-5
I don't believe he atv has a fan. He is probably hearing the hard drive spooling down.
You're probably right, it might be the hard drive. Would be interesting if a SSD was put in. I recently resolved most of the performance issues by moving away from a NAS and installing a larger drive in my iMac, mirrored using SuperDuper, but that's another story, but since I know my ATV is fine, I probably won't be looking at replacing it.

In terms of the output, even if USB could be used, it seems like there are a lot of debates on the quality and implementation. Maybe you can look at just getting the best out of the Toslink. A reclocker like the Pace Car might be an option. One thing that I'm really curious about is the Altmann UPCI (Ultra Precision Clock Injector).
Hi Tom, yes I remember emailing back and forth over the 400xi/SACD combo. Currently I'm still using the 400xi and DVD Standard w/HDMI upgrade even though I don't watch movies on it. I actually thought about picking up an SACD on ebay a couple weeks back, but never did.

Anyway, back to the original topic, I did indeed pick up an Apple TV and really like it.

I used a Nordost White Light glass fiber optic from the ATV into a Benchmark DAC1. I used that combo for quite some time with excellent results using my iPod touch as a remote. I even used an Airport Express with the optical out and achieved good results as well before the ATV arrived. I think it had to do more with the jitter reduction in the DAC1.

With the man cave rearranged and a new iMac on my desk, I'm now back to using the usb input on the DAC1. The ATV is used in the bedroom for renting movies and what not, but I have a couple ideas brewing.

Here's what I'm thinking: Upgrade the ATV drive to an SSD or CF with an adapter. This way, there aren't any moving parts in it at all. All my music is stored on a WHS so no need to sync it with the ATV. My iMac can run itunes and output to the ATV so all is well. Build and install the USB filter to provide better power to the toslink transmitter. And just like my other equipment, run it on balanced power from the PS Audio P-500. I think that's about the best one can optimize the ATV without the use of bybee purifiers or other esoterica.

Have a look at the above link Tom. They are the fellas over in Hong Kong who did the usb filter mod on the ATV. They also do comparisons using a DAC1 and Krell 400xi.
Tom, I've been extremely happy with a Van Den Hul Optocoupler connecting Airport Express to my DAC. The only thing that bugs me is having to use a cheap plastic mini-adaptor to make it work. The one I have came from Parts Express. The connection doesn't feel as solid as I want it to. If anyone can recommend a better solution, please let me know! I wish Apple would just add a standalone Toslink, but I doubt that will happen.
I'm 6ft away from a Mac Mini now and I hear nothing. How quiet do you need it?