Squeezebox Duet VS AppleTV

In answer to second part of your question:
Yes you can access your entire library on you ATV using a itouch, which will display track info and album art. Additonally anytime you add music on to your PC the ATV is updated wirelessly on wifi everytime you open itunes

you don't connect your AppleTV to the PC it wirelessly will grab the iTunes accounts from up to 5 PC's and manage them all. It's very cool and easy to use. IF you have iTunes it is super easy to use, and does movies, YouTube....

I love mine.

In answer to the first question about the Squeezebox, there is a setting on the player to choose either fixed level output or a variable level that can be controlled with the remote.

However, the subject has been discussed in great detail on the Slimdevices forum and the designers state there is no loss of detail as long as the volume is kept in roughly the top 40% of its range if you choose to use the variable output.

I have a Squeezebox 3 (now called the Classic) and a Duet player. Both are great and I'm satisfied with the user interface and extremely pleased with the audio quality through my external DAC. I've absolutely no urge to switch to anything else.

Basically a lifestyle choice - all about how you want to interface with your music.

The SB has to get the files from somewhere - there is no way to rip directly into Squeezebox... so you rip into iTunes and access the library through the SB browser, or you rip to something else (FLAC if you are a PC person) and do the same.

This is a classic Mac versus PC thing - Mac is Apple Lossless. PC is EAC to FLAC. You are pretty much stuck with the OS. The big difference here is that the SB will do FLAC...

Apple TV can be linked to your master library and/or you can download any combination of media up to the capacity of the ATV you purchase. Personally I replaced an SB3 with an ATV preferring the HDMI link to my pre-pro in my HT rig, but that was more about engineering then sound quality.

Please note that the ATV itself has no impact on sound quality. It is a question of what you connect it to.

In comparison, the SB offers the choice of using the built-in analog or feeding SPDIF to an external DAC.

I found that by the time Wayne at Bolder gets done with a power supply upgrade and an analog upgrade you have a wonderful source for much less then most name DACs. On the other hand if you already have a DAC you are happy with and it has an available input, that could tip the scales and would certainly save you the mod cost.

Obviously both the SB and the ATV can be connected via Ethernet or WiFi so that's a push.

I would have to give the SB a slight edge if your goal is a multi-room setup with each room being able to access its own music.

You can navigate the ATV with an iPhone or iTouch, or simply do it on screen if you are set up that way. There are various PDAs that can be combined with 3rd party software to navigate the SB browser. There is no way that I know of (which don't mean jack) to put the SB browser on anything but a computer display.

If you are also an iPod user, I think that it makes sense to keep it all in the Apple family.

Hope this is somewhat helpful. As I said at the top,this is a lot more about how you are going to use it and what else you have going on.