Help with Korg MMA130 amp/monitor?

[theshapecool]

Hey everyone, I'm new here but not new to music gear.

Does anyone have the MMA130 for busking?

I've got a real issue, I love the thing but the only problem I have is when I use a microphone, I cant turn it up past 1 before it distorts. I've tried all sorts of different mics and settings, trim levels, main level etc. It just wont give me any real power before it distorts and its a pain in the bum!

It works with my backing tracks fine and ive tried it with just the mic and nothing else. Can you help?