Who's using Harbeth with tubes, what speaker model and how many watts per channel?

The impedance curve for the 40.2 below. Impedance appears to be ABOVE 8 OHMS ALMOST EVERYWHERE, except for a slight dip below that value in the vicinity of 100Hz.  So some unscrupulous manufacturers would claim the 40.2, 40.2A, and now the 40.3 are a 12 ohm speaker, but given how these measurements are averaged its clearly an 8 ohm speaker so use the 8 ohm tap.

Regarding ease of drive the minimum impedance  of 8 ohms means that most if not all amplifiers will be able to supply the necessary current for a given power output level without difficulty.   Otherwise the modest 86db sensitivity and the ultimate amount of power needed will depend on the usual factors- average listening level, distance to speakers and dynamic range of the music listened to. 


https://www.inputaudio.de/wp-content/uploads/2015/06/harbeth_m402_audio_test.pdf

with respect to which tubes, perhaps i should not have made my prior statement with such ’absolute-ism’ - it obviously depends on your amp and your room

most harbeths are nominally 6 ohms, dropping to just above 4-5 ohms in the bass region

sorry about the typo in my post below - 

should read: 'with respect to which taps on tube amps to use...'

@aj523 would love to see that review translated into English, but have been unable to find it.

@pdreher 
Yeah sorry I had someone read part of it to me but most importantly the red line is the frequency response measured in axis, green is 10 degrees above, and blue is 30 degrees to the side (lateral).

I have SHL5+ speakers and used the Rogue Audio Stereo 100 amplifier (100 WPC).  
Amazing dynamic and powerful sound.  Much more powerful than my previous 100WPC cronus magnum II.  
Med/ large room.  
4 ohm tap sounded weak and anemic, 8 ohm tap much better.  
The Stereo 100 is actually more dynamic sounding that the amplifier I replaced it with, a Parasound a21+.  Should have stopped while I was ahead.