I now have two! The local auction came good again today...
A rather tidy 1965 grey Stereo 20 complete with box, manual and leads. I paid way more than I was hoping as there was one other punter in the room that obviously knew what it was and drove it right up. Without him Id have had it for £30, with I ended up payng £473 including auction fees, which was very, very close to my own red-line of £500.
The reason I paid quite a hefty wedge for something I already own is it looks totally stock, maybe even NOS even though it has a couple of minor cosmetic issues (one scratch and some slight discolouration where the octal cable was coiled on top which wont come off). The reason I suspect it may be NOS is the tube set is certainly original, all the date codes match, the three Mullard ECC83s and EL84s being a proper matched trio/quad when it comes to date codes and batch numbers, and more significantly there is not even the slightest hint of any heat marking on the circuit board around the green drop resistor. Ive never seen a Stereo 20 this clean underneath.
Leak Stereo 20 prices seem to be rocketing at the moment, some good examples going over £1k, so really I bought this as an investment. Im just going to keep it as-is as people seem to pay the most money for really good unrestored originals so they can choose their own rebuild strategy. I can certainly understand this as I ended up ripping out the previous rebuild of my bronze one and doing it with what I view as more sympathetic components. Ill try out some of these lovely tubes though!
PS Anyone know if it is possible to check the transformers with a multimeter without powering it up (which I obviously cant do)? I have no reason to suspect any issues, but it would be nice to know they were ok.