I recognise and agree with a lot of your description, but
- I don't think that the M6si is of sufficient quality for the Refs, which will only show up its weakness. The M6500 is much more powerful and cleaner sounding
- I find Chord amps sound too forward and analytical for my ears and IMO would be too much with the more forward sounding older Refs..and also for the very Neutral ATCs.
I can't comment on the B&Ws, as I'm not familiar enough with them.
- I think the Audiolab was out of its depth with this quality of speakers....I'm not surprised the ATCs sounded the way they did.
- IMO. In order to hear what these speakers can do, (if you can't hear them through your own amp), you should be using something from Devialet, Classe or Bryston. You also need a Source more in line with the cost of the speakers.
So to sum up my thoughts....I personally wouldn't judge any of these speakers based on the system they were in. I think the B&Ws came out on top, as they were comforting and familiar, especially with the Audiolab source.