Anyone Using Bose 901 speakers In A Home Theater?

Well g nakamato it sounds like time to experiment.  40 plus years is a long time to spend with any speaker.  Even state of the art speakers are going to have deterioration issues, let alone mass market items.
  Are you still in a 4 channel set up?  Is your amp driving all 4 channels?  Is your TV in the system and if so, do you have a center channel to help with dialogue?
   Your ideas about power are somewhat antiquated.  The amount of power required is most dependent upon the efficiency of the speakers.
  McIntosh gear has a high resale value.  You may be able to sell that behemoth and be able to fund a decent 5.1 surround system, including an AVR, particularly 
if you buy on the used market.  Audiophiles constantly Buy and resell gear and you will be able to get relatively new equipment at knockdown prices.

Just searched that power amp.  Someone is listing one for over $5000.00
Again, selling that off would fund  a really great sounding 5.1 system, even without buying used equipment, and it would probably sound several times better than your current set up

from 1971 till 1988 i had a 4 chanell system. from 1988 till 2000 it was in storage. from 2000 till now i only listen to music, radio and tv thru my system.  in 2011 i got the mc602 and in 2014 i got the mx132. i only use it once a week. i only bought these 2 units just to have it.

back in the early 70's there was 4 chanell and i had 4 901's. i basicly had mine setup as 2 up front and 2 on the sides.

Bose products are not about accuracy, but rather musicality. They are not designed for critical listening, but rather casual enjoyment.  I had owned 301's as well as 901's in the past and I was very satisfied with the amazing soundstage they provided.  The 301's sound "classic" in their auditory signature. Both the 301's and 901's are well suited to modern jazz and classical music. I have tried many varieties of speakers after I parted with the Bose 901's and I have not yet found an equal in terms of soundstage. All brands of speakers have their pros and cons.  If you want absolute purity and accuracy in reproduction, then look for something else.  If you want musicality and vivacious soundstage, then the 901's are perfect.  Don't be misled by those who have never owned 901's but have plenty of opinions.  My home theater consists of all Klipsch set up (the last series made in the USA with silk tweeter based horns that are not shrill or harsh), my listening rooms have Carver Amazing III+ and JBL Studio monitors, and my home office is all Klipsch, but I missed the musicality and the soundstage of the 901's so I recently bought a pair for my den.