Thought I would update my thread with my end result...
Ended up buying 2 pairs of Goldenjacks -10dB attenuators. Iain's customer service is superb - he is clearly a very knowledgeable enthusiast, who is happy to advise on what's best for your equipment (and in fact any other hifi topic we wandered off into discussing!)
They are available through his eBay shop, or a bit cheaper direct (£22 per set inc postage). Very reasonable price. Made to order and received within a week.
So what do they do to the sound?
In terms of volume control I now hover around the 10 o'clock point, which has given me a greater range of control. Not sure if the balance is better as some say it is further up the volume control, though wouldn't really know what I was looking for.
The best thing about them though is the sonic improvement they have brought on some tracks. With some high notes, for example on a couple of Adele tracks and some classical pieces, the treble used to get what I would describe as "wincing" and harsh. I had for a while put this down to the brightness of my Audiolab and MA combination, and was wondering what equipment changes I could make to bring some warmer / smoother components in without compromising the clarity and detail I had.
This I now understand though is due to the inputs being overloaded due to the mismatch between source output (2.2v) and amp input sensitivity (100mV). With the attenuators fitted I have played these tracks again and again and they are now listenable, and in fact sound great. The sibilance is cured!
My system now sounds as beautiful as I hoped it always would on ALL tracks, and for only £22 is probably the most cost effective thing I have bought for my hi fi - certainly a cheaper and easier solution than going through another upgrade round to try and solve the issue.
My advice therefore is if you have a similar issue to mine, contact Iain at Goldenjacks now!