cool G5 tweak re: optical out / sampling rates

discovered something tonight, i apologize if this is 'old hat' to some:

you can go to Applications : Utilities : Audio Midi Setup and adjust sampling rates from 32-44-48 khz and bit rate from 16-24. default is 48khz, 16-bit 2ch.

i chose to set mine at 44khz 16-bit 2ch vs the default 48, as i'm using the machine to send optical digital info via an AudioQuest Optilink-1 to a Cal. Audio Labs Sigma tube DAC, and the audio data is all AIFF uncompressed / raw CD audio via iTunes (aka, so i'd rather not interpolate / upsample, and would rather present unmolested sound to the DAC). I definately feel this change gave memuch cleaner lower frequencies and what seemed to be good degree of clarity/acuracy overall. I also (for the fun of it) bypassed my DAC and went straight into my Rotel 1055's optical in / used it's DAC, and changed the upsampling to 24-bit 48khz, interesting, but i prefer how the tube DAC sounds in my room (concrete floors SUCK).