I bought a new but faulty Redsub BT5110 off ebay the other day (gear4music), it had low distorted output so it was sold as faulty and only cost about £80.00 delivered. I thought it must be worth repairing. It arrived today, plugged it in and when I turned the mute button off - it was well loud. It seems perfectly fine so far. Hopefully I bagged a bargain. I can't understand it, I'm not that lucky!