I recently sent my MFA Lumi preamp and M120 amps to Mr.Scott Frankland for repairs and some upgrades. The Lumi was upgraded about as far as Scott could take it. The amps received more modest upgrades. The components now have a significant "wow" factor compared to before the mods/repairs. But wait, there's more....
And, per Scott's suggestion, I replaced the amp power tubes with Genalex KT 88 Gold Lion Reissues, and the amps have improved to yet another level.
Overall improvement is extraordinary. And this, in a system which sounded damn good before.
I've yet to seriously address room acoustics, but that's coming....