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

@atmasphere 

Does the zero add-on to an OTL amp basically then function as a Berning type ZOTL amp which provides that properly impedance-matched tube output stage to the loudspeaker? 

I own the 40.2 Annie’s and I just upgraded my Berning LTA amp to the Berning Quadrature z which is 220 wpc.  Whoa!!! is the only adj to describe the impact but only on certain songs have I noticed a significant increase in dynamics. 

@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).

Thx @twoleftears. This isn’t the first thread on this controversial question so do a search for my info.

I have the 40.2 Annies and I’m using Linear Tube Audio’s Zotl40 Reference amps monoblocked which is approx 90 wpc in 8 ohms. The tubes in each amp are a quad of NOS Mullard EL34 (EF2 from early 1960’s). Berning’s Zotl adjusts to the impedance of the speaker.

According to some I may be missing out on certain peak transients but given the music I listen to (and vinyl only), it wouldnt be much. Otherwise the combination is sweet, warm, beautiful and musical to my ears that I can listen to for hours without fatigue which was had been a huge issue for me.

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

FWIW. I think it helps a lot if you use the same brand preamp-amp particularly if going with tubes. Perfect synergy, zero issues, and  minimizes costly mistakes.