I have an opportunity to get a Pedulla Thunderbass ET. Testing it, I found that the active bass seems to hum and distort quite a bit, even when it is turned down low. Is that normal? (Doesn't seem like it should be!) I tried the obvious things: battery replacement, reduced bass boost, reduced amp trim. There is distortion unless I turn the bass completely off and the treble on all the way. On a cheap practice amp which can't handle the bass, I don't notice the distortion, but on my Ampeg SVT3, it's bad. I like everything else about this bass, so I'd like to figure out if it's fixible, or not worth buying. Any suggestions or information would be helpful. Thanks.