How many watts per channel are enough?

I have to disagree with some of the other posters. You should have no problem at all driving your speakers with either of the 2 amps you list. Your speakers are not that difficult a load. Also, you really can't rely on watts as a measure of how powerful the amp is. There is no common standard that equipment makers use for their ratings. They all do it their own way. For example, if you took ten 100 wpc at 8 ohm amps from ten different manufacturers and tested them all the same way, every single amp would put out a different amount of watts.

Zd542, legally they would all be required to put out at least 100 Watts. I agree that 89 dB isn't that inefficient, but 39 Watts is really on the low side for a room of that size.

Your taste in music seems sane, but speaking from experience, only if you (and your friends) drink a lot, you own a disco ball and/or play a lot of beerpong, love to dance all night to Dubstep, and your listening room is in an abandoned shoe factory, 36 watts might be light (in that case simply buy the speakers, subs, and amps from a band or DJ that gave up). A Jolida 502P with "factory upgrades" is about the same cost or less than the Primaluna. I have one (502p) running supposedly 90db speakers (Silverline Preludes...review testing noted perhaps they are less) in a room a bit larger than yours and it has plenty of power to spare, sounds astonishingly good, and includes balanced inputs and "easy biasing" (you could buy 2 wired mono and double your fun for less than the cost of virtually any other decent stereo tube amp)...I do use a REL sub with it but the amp runs full range, and has 85 to 115 watts peak depending on what specs you read. If you "actively listen" to normal music within 12 feet of your speakers, a 65 watt per side amp will give you all the juice you need unless you have hearing issues, really thick hair, or very bad taste in music...Jolidas are very rarely reviewed for some reason which is why I blather about mine. Not sure why I blather about other things, but really...who cares?

Ditto on most of the thoughts here.

34 watts is not enough headroom for the 89 db efficient speakers you have. On the other hand, 34 watts would be plenty for my 101 db efficient Zu Superflys.

Go for at least 50 wpc, preferably 75 or 100 wpc.

As others have eluded to, not all watts are the same. In particular tube amps are'nt the same as SS, also SET amp watts are'nt the same as a push pull tube amp. The most suprising is SET amps. You really can drive speakers you should'nt be able to. This may be due to the high current and large output transformers. There is also the issue of driving into clipping, tube distortion seems much more acceptable, than SS distortion.

My 20watt Ayon Spark, sounds significantly louder and more dynamic, than the 50watt Class A Pathos Inpol2, I also use.

All I am saying is, what should'nt work on paper, often seems to and vice versa. The only answer, as always, is to try the amp with your speakers, in your room.