Hi guys - thanks for the comments. :)
Brian - the Sony seems to be working perfectly at the moment, giving it a good work out over the last few days seems to have cured the imbalance issue. The ProAcs are quite inefficient so the amp needs driving reasonably hard to give a decent level. I'm really clueless as to why this should've worked but hey ho...a new amp is off the shopping list for now which is good news. Presently looking at a new dac (as you know) and possibly a new cartridge - the Rega Carbon's a hoot on rock/jazz but on orchestral it's a tad unruly, to put it mildly.
Gary - nothing so sophisticated as that here I'm afraid (I wouldn't know where to start!). Just chatting with old friends on FB whilst the TV/Humax plays through my Fiio dac into the hifi system. Does sound pretty good though. The sound producer in Vienna could teach the BBC a thing or 2 about mic'ing up and balancing an orchestra - quite a refreshingly natural sound.
A Happy New Year to you and yours. :)

