I use the DR-670 in my home studio. It has two audio outputs and must be plugged into an amplifier to get sound out of it. Optionally, you can use headphones. The bass and drums are both mixed into both outputs but some of the sounds can be panned left or right. My favorite sound, the STK3 rim shot is a stereo sample and can't be panned into one channel. So I would assume you would want to run the DR-670 into two amps or get a cable that will combine the stereo outputs into one. If you want to play bass parts only, you can just run one cable to an amp input and use the level control on the DR-670 to adjust the volume. Although the DR-670 works well for me, I just use it for drums and record my bass parts using a real bass. The DR-670 is very tedious to program but does have great sounds. Another good option would be to use Band-In-A-Box to generate rythym tracks, burn them to a CD, then play the CD through the amp using a portable player or just use a boom box. Not sure exactly what you are trying to achieve so maybe you can elaborate more on what you need. All the drums parts on my web site were done with the DR-670.
Greg
Greg's Web Page
MSA/Steel King Sounds
Complete Songs Added 6/26/2006![This message was edited by Greg Cutshaw on 29 June 2006 at 10:26 AM.]