I own a Melos preamp and LOVE the nasty-lookin' old thing. Have sent it back for repair and upgrades to Melos Audio Restoration in Vegas a few times. The upgrades were both of their design (all-tube design), and sometimes of mine (replaced all Solen caps w/ Auricaps one day for some reason)They were employees at one time that bought the company name when the chief designer and audio genius/guru decided to go do something else. They REALLY GUARD all schematics from Melos and are VERY hard to find online even. Their repair work is very reasonable and of good quality though. Havew not been in contact for a few years but I'd start there by seeing if thery are still around first.