Just purchased a used Tribbie L2500 sight unseen and have some wiring issues. Bass works perfectly fine passive, but when I engage the active preamp, i get very low output and when I dig in REALLY hard, the preamp LOUDLY distorts. I checked all the wiring and it seems to be correct and I checked all wires for bad connections or shorts and I could not find any. I'm thinking that the OpAmp is bad or biased incorrectly so I ordered a new OpAmp since it was only about a buck. Any ideas on if my preamp is totally toast and biased incorrectly or am I on the right track here? BTW, bass sounds absolutely awesome in passive mode.