Yep, two tracks, one for the DI and one for a mic on the amp. You may want to cloce mic the amp to avoid phasing issues.
What kind of bass amp? Some have a level control (output) for the DI, if yours does you might want to set the level to just above half (this works in most cases) to reduce noise and hum. You might want to try a different cable for the DI and check to be sure everything is grounded the same. You might also try moving away from other devices (amps, mixer, computer, monitor) if you have enough space. Sometimes electrical interferance will be heard on a DI even when you don't hear it through the amp speaker.