HDtracks Music Libary Software For Macs

You don't need any of those to use the Squeezebox, but keep in mind they just discontinued them yesterday.
My music is mostly on an external 2TB HD on an imac. The Touch is in another room connected via coax digital to my Anthem MRX.
I also setup Squeezeplayer and the SB server on my Macbook, so I can play the music on the HD on it to the Touch or listen to either source on the Macbook.
The ipeng app for the ipad is a great way to control it all.
As soon as I upgrade to Snow Leopard, I'm going to try Audirvana on the Macbook, considering getting a Audioquest Dragonfly to use with headphones.

Will agree with above posters - just stick with your itunes database and use a third-party player like Amarra, Pure Music or Audirvana Plus. All of them offer free trials so you can try before you buy, compare as you dare! I currently use Max for converting FLAC to AIFF - very easy to use, works like a charm and there is a tutorial on how to use it right on the HDTracks website. After initial set-up as per the tutorial it literally is as simple as clicking and dragging the files to be converted - and the software is free!

Sidssp is correct. iTunes will play play 24 bit files and does not play FLAC. you can easily transcode AIFF or ALAC which are supported by iTunes with free third party software like XLD.

One thing iTunes will not due is automatically switch between 16 bit and 24 bit sample rates and it is slightly tedious process to do so. This is one of the nice features of the third party playback like Amarra, Pure Music and Audivrana Plus which work with iTunes is the auto switching of sample rates. On top of that I, along with many others, hear significant audio quality improvements using one of these for playback allowing iTunes to simply act as your music database manager.

I've been very happy with Audirvana for HD playback.

Recently I became a new and happy user of Amarra. It comes with a brilliantly executed EQ function with many pre-set functions to use for different occassions or for room correction. For example, I use the bass boost when I want to have freinds over and listen to rock or modern music. Otherwise I am experimenting with the other pre-sets right now with the plan to do sound measurements in my listening room. That's when I hope to dial in the right EQ setting to get the best sound. Oh, and it integrates with iTunes very well. JMTC.

iTunes absolutely handles high res playback. It is the DAC and the interface to the DAC that limit how high resolution you can play.

If you are talking about FLAC files downloaded from HDtracks, that is true, iTunes doesn't play FLAC. But you can convert FLAC to AIFF or to Apple Lossless and iTunes can play them without problem.

Having said that, many third party players do sound better than iTunes. I have tried Amara and have used Pure Music for a few years. My current favor is the Audirvana Plus because it sounds best to me and its iTunes integration is the most reliable.