Have had this amp for a few years (since launch) and yesterday it stopped producing sound 
I know absolutely nothing about this type of stuff, and am stuck as to what to do. It was a very expensive bit of kit at launch and would hate to have to replace it
Any ideas what it could be? I cycled through the speakers A/B A+B B and so on and it came back, but since then it hasnt?

I know absolutely nothing about this type of stuff, and am stuck as to what to do. It was a very expensive bit of kit at launch and would hate to have to replace it

Any ideas what it could be? I cycled through the speakers A/B A+B B and so on and it came back, but since then it hasnt?