Chantaipan,
My wife and I love mega changers.
I found the Sony ES mega changer sounds better than the non-ES changer, I found the sound to be much fuller.
I like the Sony because I have never had a Sony product go bad on me, it holds 400 discs with title display, and it works with Slik-e (an amazing litle toy!) so we have instant access to every single track.
Using One DIP with the ES improves the sound nicely.
The non-ES changer benefits the most from two DIP's, with the first DIP improving sound substantially.
I used damping material on the outside of the changer. I was surprised how much it helped. So much so that I ended up covereing most of the sides/top. Damping around the 'hump' on the ES had the greatest impact.
Whish I'd done the bottom before I filled it with disks!
Next, I will see about the power cord. Don't want to open the thing up, so maybe some ferrite rings or some shielding on the cord. I have it plugged into a Versa Woodblock, but that didn't seem to help much. It will (eventually) get it's own dedicated power line. AFter that, time to experiment with isolation and mass.
I'd love to hear from other mega changer users and what you've done to improve the sound.
KP