$40,000: What 2-channel system would you build?

Honestly I don't remember. What I remember is that most of the rooms were awful, I heard $100K+ stacks of Esoteric and other gear and that the Vandersteen room was till way too expensive for me, but at least it didn't grate my ears.

What I heard at THE show was probably this same setup as in the RMAF:

https://www.stereophile.com/content/vandersteen-k%C4%93nto-carbon-loudspeaker-and-m5-hpa-amplifiers-...

i could go any number of ways, but, I would always start with high or reasonably high efficiency speakers because I tend to only like lower powered amps; even if I had an unlimited budget, it would be a low powered amp (pushpull or singled-ended tube, perhaps a First Watt solid state amp). To save a lot of money on amplification, I would build an Elekit 300B kit amp which would hardly dent the $40k budget (I think one with decent transformers costs around $3k).  

Among the decent sounding high efficiency commercial speakers, I would consider an Audio Note AN-E at whatever quality level I could get while spending up to $20k or so.  My other choice is the Charney Audio backloaded horn speaker with the AER driver ($17k); I would seriously consider this speaker even if my budget were $150k.

The rest would be spent on sources (music server/DAC, primarily, not enough budget to also get a worthy vinyl setup), cabling and power line conditioner (something from Isotek).

@OP,
I don't think you listed your current speakers. At least, I haven't seen them on a quick read.
Bob

@larryi I'm more apt to go this route.  But... I can't do ultra low power. 

@gdnrbob  Bob, I've currently got Wilson Audio Sophia 3.  I'll be selling them, and rebuilding a system in about 6 mos.  Likley, I'll go back to Wilson and ARC.  But, we'll see.  This post has made some convincing aregumetns to consider others like Audio Note and more.