I have the Audiophile version with the real tracks and the real drums located on the 1TB external drive provided by PG Music. Biab 2011.5, RealBand 2011.5, and PowerTracks 2011 EXE. files are all installed on the C:\ drive. I notice that when I start RealBand, it initializes the accompaniment files on the external hard drive for 30 to 45 seconds - even though I have not touched the "generate" push button, and I only have "User" Midi files. I'm not currently using Biab, but I suspect that parts of it may be called by RealBand.