My Yamaha THR10 cuts off completely after a few seconds when playing on battery power. This is the 2nd unit that has done this. I just exchanged it yesterday for a factory new unit, took fresh batteries that had maybe 45 minutes on them (bought new for this amp) and installed them in the brand new amp. Noodled away at the store for maybe 5 minutes and it never cut off. I crank it up this morning for the first time at home with the gain/master SLIGHTLY higher than I had it at the store and it cuts off in less than 5 seconds. If I lower the master and take it off the higher gain settings, it doesn't cut off as quickly, but still cuts off entirely. Dead. No sound. It does not fade out gradually, spit or sputter. No sir. It just stops instantly like you ripped the cable off of its tiny speaker(s). Nothing is different except the guitar/cord and my latitude/longituge. I connected the ac adapter and played for guitar 10 minutes at much higher gain/master settings and had ZERO problems. Also on this amp, just like the other one, when you plug in an ipod/ipad/c.d. player in to the auxiliary input and play music via battery power and at a higher volume level, there is NO problem. The issue is just playing guitar on battery power - the EXACT reason I bought this lovely little digital/computerized device. This does not make me happy. Does anybody have any ideas? I know the store will think I'm crazy. Hell, I think I'm crazy. The store said that they've sold 15 or so with no issues. May have to call Yamaha before contacting the store again. Update: Just tried the amp with 2 more guitars and 2 different cables. NO CHANGE in the problem!!!