I have an iMac, connected to a DAC (part of a stereo) via a optical cable. Even though I have my audio files ripped at lossless ( managed in itunes) the sound quality is notifiable lower in quality that using a traditional CD player plugged into the same DAC. I am not a regular MAC user, and need some assistance; I think there may be a dumped down audio setting that is lowering bit rate, etc. somewhere I can not find. IN PC itunes,I noticed there is a preference setting in playback that lets you configure Bitrates for audio playback and Bits Per Sample For audio. The default on PC install was pretty poor. So where is that setting on the MAC?