30 to 50 watts seems to be all I desire

Listening to mainly Jazz at volumes less than 85db, normally.

I used to listen close to 90dB when I was younger(20+ to early 30s) with peaks hitting 100dB. Now a lot older, my average listening volume is 65dB. At these levels, any amp would do it.

I occasionally listen at 70 to 75dB only for a short period of say 10 to 15 minutes.

The average SPLs I recorded with the Radioshack meter (~65dB).

 Power requirements can be all over the place depending on speaker efficiency, volume, room size, and even more. To get to the point, so many years ago, I had speakers with 103db sensitivity. They were horns of course. I ran SS mono blocks rated at 90 WPC, and the meters never moved, nor should they. The bass was like I have never heard since, but midrange horn was not so good.

  My point is that there are too many variables to set yourself thinking about a certain amount of power before understanding the needs of your listening experience in the first place. 

Another component to this topic is the input/output sensitivity of preamp/amp. I had a Decware Torii Junior, 20 wpc, with a preamp, Canary C630, max gain of 9db. Couldn't get over 90db volume (at 10') with preamp wide open. Tried a Rogue Audio RP-7, with 14db gain, could not get even 70db listening volume cranked up. 

Input sensitivity of the Decware amp is set to 2 volts, most are 1 volt or less. So it takes twice the preamp signal to get to same volume. I now have a PrimaLuna Dialogue HP, with input sensitivity of 1.2 volts. Almost the opposite issue now, same Canary preamp, volume set at 2 of 10, dB listening volume is plenty, 85+. At 4, music transients are >100dB. 

Addendum

The PrimaLuna I referenced has 72wpc with current output tubes, so in a different class than the Decware. But input sensitivity of amp is still relevant. 

That Decware amp had gorgeous sound though! Just wish that input sensitivity was adjustable, 20 watts might have been plenty.

I own the Magnepan.7’s and l have two amps A VAC PA 100 100 tube amp and a Spectron musical MK lll SS amp As you know Maggie’s love watts/current My VAC sounds magical with the Maggie’s at 100 watts per side But when l use my Spectron with 500watts@8ohm 650@4ohms and 1,200 watts@1ohm and the capability of producing 60 amps for 500 milliseconds, it really makes the Maggie’s come alive with dynamics, inner detail and sound stage

Watch "magnepan 7's doing their thing" on YouTube
https://youtu.be/bofnCCYuR48