AUDIO RESEARCH SP-10 MODIFICATIONS

Does the manufacturer still service these? I had an SP-10mkii that went back and forth to ARC when WZJ was still around. We tried gel tube sockets to minimize microphony- didn't work; and the factory hot rodded it per something that HP discussed- I can't remember what was bypassed in the hot-rodded version. To me, this model was the height of the original tube preamp era for ARC. There have got to be schematics for the unit, no? And some restoration shops could follow those. I think Audio Classics (or whatever that used McI shop is called) restored a Marantz 7 for somebody on SH forums who bought a unit which suffered a gutted  phono stage that had been replaced with solid state circuitry; the shop restored the unit to original design. 

Try Audio Classics- they do sell used ARC and I know they had a lot of work to do on that Marantz 7, which had been bastardized. They won't be cheap. Bill Thalmann, who did a fair amount of pieces for me, passed, sadly. Good luck, the SP-10 has a well deserved place in the history of tube preamps, though a tad microphonic.