I purchase a Fender Rumble 350 with 2x10's last summer. I noticed a scratch sound like a blown speaker when I play on the E string about a month ago. Tried my other bass on it with same problem (both are active, new batteries). So I proceeded to take it back to where I purchase it. When their technician plugs into it it sounded great. Plugged in different basses with no problem. So I take it back home and get the same problem again with both basses. It sounds like it's from the speaker on the left. Both basses do not create the sound on my fender TB-1200 and 6x10 neo. What the heck is wrong? Why does it sound crappy when I get it home?