I just picked up a GK 1001RB (first generation) from a fellow TBer and played it through my Hartke 410XL for the first time last night. IMHO they were meant for each other. Now I have a dilemma. I play an active Spector and had planned on using a Radial JDI. I'm so happy with this GK1001RB that I'm now considering using it for gigs and eventually getting a new one (I bought it as a rehearsal amp only). Does anyone have any experience with the built in DI? How does it compare to using a passive di? I am very well aware of the differences between active/passive in theory, but am looking for input on actual experience.