I recently purchased a used Hartke 4200 Pro (rated 400 watts @ 4 Ohms) to replace my ancient Hartke 4.5XL (rated 275 watts @ 4 Ohms). My head is a 20+ year old Hartke 3500 (rated 350 watts @ 4 Ohms). Here's my setup (in order): Bass to Petersen Tuner Stomp Box to Boss Chorus Pedal then to passive input Hartke 3500 head with BBE Sonic Maximizer (through the effects loop) finally output to Hartke 4200 Pro. When I Play my Rickenbacker 4004 Cheyenne it sounds like the "Voice Of God" to me. The tone I've always dreamed of. -However- (here's the problem) When I switch to my G&L 1500 (passive setting, series pickup setting) input into the passive (or active) input into the amp head, I experience sound loss. The low frequencies disappear and I'm left with thin clanky weak top end boinks. Sometimes the sound goes quiet altogether, then will weakly return only to fade again. Am I tripping a protector? Are the pickups on the G&L just way to hot? Is the Cabinet sucking too much power from the head? Is a preamp tube on it's way out? Do I have too many "toys" inline or looped? I don't want to part with my Beautiful Red flaked G&L 1500 with the maple fingerboard and 1 3/4" nut. It excels at the funky thumps & pops.