Testing older gear is interesting because many of us have older gear. The question we face is a simple one: can I achieve sonic improvement by getting something new, or is the old stuff so good that no further sonic improvement is possible?
In my own case, I have tended to keep gear for very long periods of time because what I had was top quality in the early 1970's (Quad 33/303, Quad ELS57). Keeping gear for such a long time was financially very sensible, I think. I finally replaced the speakers some ten years ago with Quad 2805s, and more recently I bought a refurbished 2x140 watt Quad 606-2 because I needed more power for the new speakers and was playing in a much larger room. The sound quality improved, but only at higher levels. I am not convinced that a modern amplifier will bring further sonic improvement but I am happy to be proved wrong. So yes, I would love to see Amir measure the Quad 606-2 or 909. A few months ago I decided to replace the almost fifty year old (refurbished to be sure) Quad 33 pre amplifier with an RME ADI-2 DAC. This has proper digital inputs instead of the assortment of internal DACs in the sources that I was using, and the sound improvement is clearly there. My hunch is that the improvement is primarily due to the better pre amplification afforded by the ADI-2, because the Quad 33 does not really measure that well by current standards.
My point is that I had to take these decisions about replacing old but once high quality gear without measurement data, and it would have been nice to have those.