I moved to a new flat about 5 mnths ago (plugging the computer back in after the move is when it died).
before I moved ,I boxed up my kit and took it to my brothers .
Just to be on the safe side 
I had been without my kit for about 6 weeks (no rush to get it back , plenty of things to do , blah , blah blah )when my brother asked me if I would house sit for a week .
I said ok and thought whilst I was up there , I,d build the system back up and have a blast (nice big room , so potential for great time)especially as I wasn,t ready to have my system back at the new flat ( crap acoustics , lots of work needing doing ).
I got up to my brothers a couple of weeks later and stuck the system back togther .
I then gave it a few hours to warm up and it sounded.....crap .
gave it a day , still crap . Gave it the week and at the end still crap .
The only variables really are the room and the leccy .
As far as the room is concerned I,d have bet money on it sounding better than the small room I,d been using .
I was using all my isolation trannies and my filters .
My money is on the fact I didn,t have a seperate ring for the Hi fi .
I,m not even bothering to get the system back untill i do the mains , that,s how strongly i feel about it .
I know I can get a good sound out of my system , after all I,ve heard it at my old flat .
I,m just wondering if this is where your problems lie .
Just a thought 