I have the Roland BA330 and my wife and I love it. She plays violin and I play guitar, mandolin, ukulele. This amp puts out 40 watts of power, enough for a small-to-medium size room. It has 4 channels, 1&2 can take a mic or an instrument, 3&4 are both stereo channels, so it's actually possible to plug 6 instruments into this (use 3&4 as 2 mono channels each). It can run on 8 AA batteries or on AC power. It's the same output whether on batteries on on AC. There are other Roland battery powered amps which put out 40 watts when plugged in but only 30 watts when using batteries. This BA330 can run on batteries for over 8 hours. It can use rechargeable batteries but there is not recharger built into the amp. It's got a great acoustic sound. It comes with a speaker stand mount built-in so it can be put up on a stand. It has a kickstand so that when it sits on the floor it can be tilted back. It also has a special output so that if a person wants to buy two of these for a more powerful setup, one of these can be used as master and the other as a slave, or they can both be used as masters with their own inputs and output sent to both sets of speakers, for a very nice complete PA system. But so far my wife and I have done some great performances with only one of these, and I've used it as a PA amp with my community band when we didn't want to bring our full-sized system.