Integrated Amp Curiosity

This is triggered by a recent post by someone who is reportedly perpetually curious about amps, in general.

In the last several years, while shopping and auditioning integrated amps, speakers and TTs, I spent a fair amount of serious seat-time with several integrated amps in relatively well-controlled demoing conditions.  There were four in the price range I was looking at that really stood out and impressed the heck out of me:  Musical Fidelity M6si + McIntosh MA 5200 + Luxman (can't remember model but competitor to the MAC) + Simaudio Moon Neo 340 IX.  I actually bought one of these, but I won't say which one in order to encourage honest feedback, if there is any.  After that purchase, I spent a lot of serious seat time with one of these others auditioning speakers.  That one keeps haunting me and making me wonder if I would have purchased it, instead, had heard it before buying the one I did.  I'm sure you audiophiles out there will know exactly what I mean.  So, I guess my question for the peanut gallery is this:  Have any of you been able to do fair A/B comparisons of any of these amps and, if so, what did you think?