Apple Lossless sound quality comparison between AppleTV and SqueezeBox 3

Hi, I have been using a SqueezeBox 3 with Slim Server backend running on a ReadyNAS for more than 10 years now. I also use an external DAC from the SqueezeBox. All my music are apple lossless ripped from my CD collection.

Recently, I've started to use my AppleTV and stream my Apple Lossless music to it, and also use the same DAC from the AppleTV.

I noticed a big difference in sound quality - the music from my AppleTV sound much better than the SqueezeBox. Everything just sounds better with better imaging, more details, and better dynamic range. I started to do some research to find out what could be the difference. I noticed that Apple Lossless streamed from the Slim Server must first be converted to PCM before streaming to the SqueezeBox using some program called faad. I now think that there might be some quality loss during this conversion to PCM by faad. Given that AppleTV is an Apple product, it probably does a much better job converting Apple Lossless into PCM before hitting my DAC. That is just my hunch to try to explain why AppleTV sounds better than SqueezeBox. In my case, they are both acting as a transport because they both route to the same DAC before going into my Amp.

Does anyone here have the same experience or able to shed some light on this?

Thanks very much.