Shocked. Need Opinions. How muck power do I need?

Always have much more power then you need ,good rule of thumb 

for if playing loud you don’t want to be going into transformer saturation and distortion , they say in transients you can have 10 x the power for short burst 

in transients milliseconds ,the power supplies and. Ample capacitances is very important .150 8 ohms 300 at 4 ohms is a solid amplifier double down 

if it cannot come close then average at best performance .the output-devises  such as how many Mosfets per channel will dictate current delivery to complement the transformer size ,and filter capacitance. My Coda amp 3k transformer ,almost 100 k in filter capacitances ,and 20 15 amp Mosfets  per channel , 100 amp  capability .

it has dual 16 amp slow blow fuses on the back that says a lot about current delivery and 4 more fuses inside the unit.

if tube then calibrated different for the size ,quality of the power transformers  and chokes ,power supplies. from my experiences which is over 4 decades .

With 40W it will be -2.7dB.  Perceived loudness will be 16.6% lower (still over 100dB)

I listen to Mostly Jazz and some rock and I bet I don’t go past 5 watts 90% of the time. I actually have two systems.  one has 40 watt mono blocks and it can blast you out of the room the other has 300 watt mono blocks and I bet I’ve never used 100 watts. I also have a subwoofer, that I rarely use because on the upstairs system, I rarely need it.  So it’s probably going back into the downstairs system.

I believe my Pass X250.8 pushes about 12% class A and I never had any needs to out of it. About 30W is plenty as long it is backed up with huge power supply and enormous banks of capacitors 

I haven't owned an amp over 6 watts per channel for quite a while.  My new amp weighs 300 lbs and makes 4 wpc.

--Jerry