M-Audio Fast Track Ultra 8R problem

[SAQ76]

Hi.
I am using Pro Tools 10.3.1 with an M-Audio Fasttrack Ultra 8R. I went to record at another location yesterday and amidst a lot of chaos I think the M-Audio was powered by the wrong adaptor (Laptop adaptor). When I returned home it powered on but nothing came out.
I tried reinstalling the software (twice), also installing the latest driver each time.
All functionality seems fine apart from the loss of output volume. It powers up OK. All inputs seem to be working OK. However, the main output volume needs to be turned right up to 100% to get very little output (usually, around 4 gives loud enough output).
I am always so meticulous that I really have no idea how the power supplies got mixed up. I always pack each adaptor in the case it should be in.
I have seen a similar post on this forum that suggested part of the board may have been fried. If this is the case the cost of repair would suggest a new interface.
Anyone any ideas what this is, or how to rectify?
Ideally, I want to make this one work but if I am stuffed and need a new one what is the general consensus regarding the best 8 input interfaces in a similar price bracket to the Fast track Ultra 8R.
Thanks,
T