Have you popped the top had a look in the cabs? I was reading up on stuffing and cabinet sound, and came a cross this article:
The Cabinet Face & Stuffing
They say that cotton, followed by fiberglass, are the best materials, and that neither are much used today for various reasons, not least of which is cost. Scroll down the page a bit to get to it.
Here is another internal "tweak" I came across. I should say, I haven't tried any of these, but you might find it interesting. Not sure what's inside the Ohms, as I haven't looked inside yet.
Mapman,
I sometimes miss the tone controls and loudness button on my old McIntosh. I worry about my ears as I get older, and a little bump in the treble and bass could be useful here. But just try to find a preamp with these today! It seems only McIntosh still includes them.