Disabling Ultra won't be a major performance hit. The sustained throughput requirement for 32 voices of 24 bit audio @ 48k is only pushing a little over 4MB/sec over the SCSI bus. Synchronous transfers (Fast SCSI) over a wide bus will be more than adequate. Running in Fast-Narrow mode should not hurt your performance either. You should still be able to get 32 tracks across both drives. As for the drive's access time, well, that's an internal function of the drive. It's determined by the rotational speed, seek time, and command overhead. That won't change, regardless of whether you're in Ultra mode or Fast mode. Command signals use a separate set of lines on the SCSI bus, and they are not impacted by the transfer rate over the data lines. The only thing that changes is the maximum burst rate over the data lines of the bus. That rate will drop from 20MB/sec to 10MB/sec, but it shouldn't have any detrimental impact.Keep in mind, drives on the PTIII Disk I/O handled 16 tracks of 16 bit in Slow SCSI mode for years, and that's at a maximum burst rate of 5MB/sec. If you are using a wide SCSI accelerator card, and you're using narrow drives, you'll need to get a 68-pin to 50-pin adapter that terminates the high byte of the bus. Adaptec has this part, as does Granite Digital. (Adaptec's is less expensive.) If you are running narrow drives off of a wide bus without terminating the high byte, you could see -9073 errors -- though you'd mainly see bus hangs*.