I assume you're using the toslink optical output on the iMac? Check to be sure you're actually importing the songs using the codec you've selected (apple lossless). Maybe something as simple as dirty CD's?
I have a 2005 Powerbook G4 and playing Apple Lossless (or even 256k / 320k MP3's) across wireless to my Airport Express, (which is attached using toslink optical to my DAC) sounds marvelous! My ears can't tell the difference between that and playing the actual CD.
FWIW My DAC is the Stello DA-100, CD Player is a Theta Miles, Amp is a Cary SLI-80 and speakers are Taylo Reference from Tyler Acoustics.
I have a 2005 Powerbook G4 and playing Apple Lossless (or even 256k / 320k MP3's) across wireless to my Airport Express, (which is attached using toslink optical to my DAC) sounds marvelous! My ears can't tell the difference between that and playing the actual CD.
FWIW My DAC is the Stello DA-100, CD Player is a Theta Miles, Amp is a Cary SLI-80 and speakers are Taylo Reference from Tyler Acoustics.