Hey everyone, I've got a subwoofer that doesn't function properly, and I suspect it may be the plate amp. Here's a rundown of the symptoms and the tests that I've performed: 1. Subwoofer is inaudible during normal operation, but the power light is on. 2. Cranking the volume on the receiver to the maximum will produce some bass output, but still very low levels. 3. The problem occurs regardless of whether I'm hooked up with the high level input or the line input 4. Crossover is set to the highest value (150Hz) and subwoofer volume is set at the maximum 5. Power is set to "On", not "Auto-On" 6. I have tested the sub with another receiver, but the result was the same: low output even with volumes cranked First, let me state that my definition of "low volume" is "I can barely hear it when my ear is right next to the driver". I can confirm that sound is playing through the subwoofer, not just power noise, so the inputs are definitely working. These facts have led me to the conclusion that my amp has gone bad. I pulled the amp out of the subwoofer, and I can't see any damaged or fried components, bad solder joints, etc. It looks fine. Now I know that I could just order a plate amp for $100 and move on, but I'd rather not spend the money when there is likely just one component in the amp that has failed. I'm looking for advice from people who have encountered a similar issue, and what component they suspected was the cause. I'm an electrical engineer, so I have access to plenty of tools, measurement devices, and soldering equipment. Unfortunately, amplifiers were never my strong suit in school, so I can't speculate what might be causing the volume problem that I'm having. Maybe a bad op-amp? Broken feedback loop? Please chime in with any experience or advice that you may have, even if it's directing me to another forum! I've been an occasional lurker around here, but this problem has finally brought me out into the open. Thanks for any help that you can offer!