Are future improvements in Amp/PreAmps slowing to a crawl?

I usually tell people that the room is 50% of the system. There's not a lot you can do with the very best system if the room sucks. Conversely a very modest system can do great things in a good room.

If you had the perfect amplifying method - a pair of Radio Shack book shelf speakers would still give you incredible imaging.

I used to work at the Allied Radio service center in Minnesota. Radio Shack speakers imaged just fine if they were set up right, even with one of their lowly receivers like the STA-76. If you put better gear on them they did even better. One of their speakers used the Lineaum tweeter; Tandy bought out Lineaum just to get the technology for a $250.00 pair of speakers. They got good reviews in TAS on that model FWIW.

I still have a pair of Radio Shack Optimus Pro LX5, which has the Lineaum tweeter. While it's no ESL, the tweeter is way better than a lot of domes.

Humidity, air temperature and air pressure should not be a SQ problem for anything the size of a living room or smaller.

In the early days of jazz, some bands (or house parties) are said to have been heard 1.5 to 3 miles away, and some say it was partly due to the high humidity in the NoLa air.

" I have seen the future, I can't afford it"

not really

i suspect Ralph is right
There are plenty of frontiers to be pushed back

i do have much much respect for Nelson and he is a deep thinker and a doer - you don't always see those together.. my first real high end amp was his 400, probably should have kept it...

the pount about what people hear hear and how is critical, iMO critical to moving forward in a science based way vs opinion on flavors...

for example 30 years of work at Vandersteen on the importance of preserving time and phase and now MQA and the recognition of spatial blur and human sensitivity to blur vs the IMO previous holy grail of flat response.

a systems thinker might say MQA is no advance if you feed a cleaned up temporal signal into an amp with high levels of negative FB

so IMO expanding the frontier is more about alignment of design philosophy across the system vs just box obsession...

putting my $ where my ears are
ordered Vandersteen amps

some innovations:

built in power conditioning
built in HRS isolation
no digital chips in the analog control circuits
unique topology with 5 parts in signal Paton emitervresisters
liquid cooled
list goes on
and on

so yes innovation alive and well
and frankly IMO a very exciting time in Audio