I'm sure this amp was a formidable performer when new and would be a decent performer now depending on the depth of restoration. It would be interesting to see a magnified and averaged residual distortion measurement at the one watt level.
That being said, looking at the build quality of the unit in the video and quality of restoration pictured, I would hesitate testing a unit like this for fear of blowing it up.
Thanks for the reply.
My unit was one of the later models with the revised phono board that supposedly took care of the oscillation issues in earlier models. Even though it was operational, very clean and unmolested internally when I purchased it over four years ago I had it refurbished as a precautionary measure, ~300 components were replaced with high quality modern equivalents. Since then I have been using it almost daily without a hitch. I recently checked the Bias & DC offset and everything was spot on.
I also purchased a full NOS set of the almost unobtainium high speed Sanken outputs (2SA1068 & 2SC2493) as a back-up just in case.
I imagine it would survive a test OK as long as it's done within reason. I recently saw a test report here that
@amirm did on an even older Yamaha A-1 Integrated that appeared to still have many of it's original caps and I believe it survived the AP testing.
This X1 is one of the quietest amps I've had in here and it sounds wonderful. I've had it driving B&W 805D2s and it sounds excellent. The presentation is very similar to that of my Benchmark AHB2.
Maybe someone else in the NYC tri-state area can test it for this site. It would be interesting to see how far they really pushed the envelope with this amp.