You are somewhat mixing your terms. ATA-6 is an ATA standard, and all ATA-6 drives are IDE interface drives. Serial ATA 150, also called SATA1, is a transfer mode used by ATA-7 serial interface drives -- though not all ATA-7 drives are serial interface, they may also be IDE interface.
Anyway, the Phatnoise DMS cartridges use IDE drives, so you want to look a drive that uses an IDE interface, not a serial/SATA interface. To answer your question precisely, an ATA-6 drive will work, and a Serial ATA150 drive will not work at all. Easiest way to find a compatible drive is an advanced search on newegg.com.