No the difference is in the compression format you use. Apple's lossless format is kind of like making a .zip copy of the original where it technically is smaller but no data is lost. If you use ACC or MP3 you'll encounter compression related sound quality degradation to some degree depending on sample rate you use, the higher the sample rate the larger the file. This is why I use Apples lossless, for all intents and purposes it is a direct copy of the original. There is a good descriptor of the different compression formats on the Klipsch web site but searching for it is counterintuitive.
R/Jim
For more information look in my System Profile