I got a new MB115 from RMC Audio and played with it today. Even at low volumes it rattles and it even sounds like it is distorting even at the lowest volumes. I moved it to another room (in case I was rattling something in the room close to the amp) and it was still doing it even at low volumes. I can't tell if it's the speaker or something in the chassis vibrating but it seems to only do it on certain notes (particularly on the A) string. I followed the manual and set the master to 3 o'clock and adjusted the input to desired volume level. Still doing it. Amp appears to be defective. So I call RMC Audio to see about exchanging the amp for a replacement, they tell me it's a GK warranty issue and they can't exchange it. They have me work directly with GK, even though the amp is fresh out of the package and I've owned it a whole 25 minutes! I'm really P*$$ed off! They wouldn't even let me upgrade to something else. They said they can't take the amp back and I have to work directly with GK to resolve the issue! GK is in CA and I'm in OH, so I'm looking at 7 days to get it out there and they'll probably d!*k with it for 2-3 weeks and then ship it back at which point, I'll wait an additional 7 days! I cannot afford to be ampless this long. I got this for quiet upright gigs and the occasional electric gig and sold my other amp gear! I guess that was a big mistake but the wife wouldn't let me buy another amp until I sold my current ones. Lesson learned: Even though some online retailers can offer you a much better price, you lose the support gained from buying local (like GC or something of the like). It's a gamble and I lost at least for 4-6 weeks! I'm very disappointed and will not buy from RMC Audio ever again even if they're prices are cheaper! I'm going to be ampless unless I can convince my wife to let me go to GC and buy something else.