Upgrades for Magnepan 2.5R's?

I've had a beautifully mint pair of 2.5R's for years now, and I love the way they sound. Occasionally though, I find myself wondering if there are any tweaks to the electronics that the average user can do to make a significant difference. I'm handy with a soldering iron and confident I could build/upgrade something if I had simple instructions, but I'm not an EE. And, while I'd love to go out and buy a set of 3.6R's or a high-end external XO, that's not likely to happen right now so we can skip those suggestions :)

My Maggies are being driven by an equally beautiful/vintage pair of Carver Silver-9t's, although I have an 806x and a 705x if multiple channels can be used to better effect. My RCA connections and speaker wires were hand-built by me and are fully shielded, OF silver-plated copper with silver-plated shielding.

I'm using Carver's SD/A-490t CD transport (tubes on the output stage and a built-in volume control so no preamp is necessary), and peeling off frequencies below 80Hz through a 13" Sunfire true sub. I have other subs lying around too, including several from Energy, and I've tried them in different configurations but found I go back to the Sunfire.

My last system upgrade was to have Bob Carver sign my 490t... I'm sure it helped, but I'm open to other ideas.

Any suggestions?