I have a SWR Workingman's 15 combo that I'm trying to use with my Sansamp Bass Driver DI. According to the Sansamp manual I should be able to plug the output into the effects return on my combo. That should bypass the SWR preamp and allow me to use the Sansamp as a pre and the SWR as just a poweramp. When I do this I get some distortion when playing hard. I've tried lowering the gain on the Sansamp, as well as the bass control. The overdrive is all the way down on the Sansamp. Any ideas? I was hoping to have the best of both worlds with this gear. Super modern tone with the SWR and good tube sounds from the Sans.