If you have a hunt around studio/professional suppliers, you can get studio quality parametric equalisers, which take the output direct from your source and reshape it before your amp. They can be expensive, but don't add noise to the system and allow very very accurate gain adjustment at various frequencies, which you can tailor for your hearing loss.
Another approach would be to bi/tri-amp your system, with power amps which adjust the input gain (i.e. Chord) - you can then step up the mid/treble until it sounds natural. (they are always bloody expensive though!!).
Cheers
Rod.