I dont have a MAC but just upgraded to the Audiophile version for Windows. 'I' can hear a big difference, but some might not. There is close to 700GB of data on the USB drive.

In addition, I bought a 1TB drive ($128) to use as my day-to-day use drive and keep the PG one stored away...but that's me. You can use the PG drive directly, but I feel better having a backup drive.