It’s an accepted “best pactice” of most audio software providers that audio files should be recorded on a hard drive other than the Mac’s Startup drive (i.e. the drive on which the operating system is installed). You can probably get away with recording a few tracks to your computer’s Startup disk, but for the best performance of your Apogee recording system, record onto a separate ATA/IDE, SATA, or FireWire drive whose spindle speed is at least 7200 RPM.