Do you mic, or line out to the PA? I found that even with just the DR103 and the SVT cab that the stage volume got pretty loud. Of coarse you just MUST get the tubes working to get the amp showing it's true character, we all know that. That is not only with cranked Marshalls, it applies to tube bass amps too! Have been fiddling with a SVP-PRO with an an old old Altec power amp bridged 150x150 to 300 watts mono. THE BEST bass amp I have ever had, hands down! You can crank the FIVE 12ax 7s and still get a driven tone without the overwhelming stage volume even with the SVT cabinet! In all my years of touring with Acoustic 360's and 371's, I only wish we had that technology back in the 70's!
But, NOTHING like a tube amp for bass like a Hiwatt or an SVT if it works with the stage volume that you can live with. Scott, your bass rig sounds AWESOME! As a fellow 60's T-Bird fanatic, and I want to commend you for all the repro parts and your enthusiasm for us fanatics of the old T-Bird! Your playing is KILLER BTW!!!