Since this discussion seems to be making its way back to GK, I thought I might add another suggestion that I use quite regularly. Although I do use it alone, I'm not in love with the GK Combo sound. What I have done to improve on the sound (when I don't mind carrying a few extra items) is to bypass the GK preamp and go right in through the effects return. But first, I run my Realist pickup through a Sadowsky outboard preamp and sometimes then through an Aguilar tube direct box. So the chain is: Realist, Sadowsky preamp, Aguilar DI, effects return on GK. Control the volume on the GK but nothing else. I usually run the bass on the Sadowsky all the way down and the treble all the way up. I get a very warm, pleasing sound (more so than the GK preamp), some nice punch and good cut-through.
Recently, I traded a cabinet for a Fishman Platinum Bass Preamp and substituted that for the Sadowsky thinking it has more EQ options. Oddly, I found the sound to be almost identical to the GK preamp sound even though there is one more band of EQ on the Fishman.
I haven't tried an AMT mic through this set-up yet, although, given the yearning for the "My Bass" sound on this thread, maybe I should. I'll have to think about what I would use as a buffer between the AMT preamp and the GK, though, as I think this is necessary. Maybe I'll try the Raven Labs bass blender which I haven't had the need to use in some time. That will also give me some EQ options. I don't think the Sadowsky would give the desired result here nor do I think the Fishman will either.
More food for thought.