Lostbears quote,
"I would see if you could borrow a newer amp from your ARC dealer. ARC solid state amps have come a long way since the early 90's and the D240 mkII. I think that would make the most significant change."
I don't know if I would go that far. Have you ever listened to those amps? You might be right, but if the D240 is part of the same line that the D300 & D400's were, I wouldn't be so fast to get rid of them. I've always felt that the 300 & 400's were very underrated. I almost bought a 400 but went with a VT100 instead but I know I would have been happy either way.
Overall, I do think you are correct in that SS has come a long way. I'm just suggesting that even though the amp is old, the sound quality may still be very good.