Pass....Accuphase....or......

I drove mine with a few different amps, the Luxman M800 was probably the most solid with them. That was 60/120. The 590 was okay the 550AXII for low levels. You need to hear a few amps and align with your preferences and circumstances. I’ve had a few Ayre amps, dealer friend demos but liked the Luxman better.

One great sounding combination I heard them with was the Audio Research Ref 110 with Ref 3 preamp.

As for lighter load, I would guess that the impedance curve on these isn’t horrible, but agree with Ozzy you wouldn’t call them high efficiency. I owned the Otello’s, much easier to drive with 93db eff I think. I’d say they Otello's are on the lower side of higher efficiency at best. Drove those great with 30 wpc tubes.

@atmasphere Relaxed, yes (laid back, no) effortless presentation is probably what I call "air" in the music, as in a big concert hall. "even at higher volume levels"...then you need dynamics, otherwise it becomes a  flat/compressed presentation. I don't now about the tricks with distortion, you have to talk to Nelson about that ;). The best amps I ever heard were BIG Audio Research monoblocks and BIG pass Labs, talk about effortless! But I can´t afford such a system....That's why I listen to live music whenever I can.....after all: it's the real thing!

@southofdallas This is exactly why its a good idea to use speakers that are easy to drive. You don't have to sacrifice any resolution to have easy to drive speakers. Lower efficiency speakers tend to have something called 'thermal compression' which is caused by heating of the voice coils. The higher the efficiency of the speaker the less compression you get.

When a slightly lower power amp is driving higher efficiency/easy to drive speakers you find you can get the same effortless quality.

I always associated 'air' with ease and space in the highs. I've not heard of it used in the context that you do; probably a topic for another thread. 

@atmasphere "I always associated 'air' with ease and space in the highs. I've not heard of it used in the context that you do; probably a topic for another thread. "

Pretend yo are in the Berliner Philharmonic concert hall....you listen to a big orchestra playing very powerful music, the volume is high but never compressed, it is just floating around (not only the highs). No speakers in this world can do that but our ears together with our brain can let us imagine that we are there when we listen at home. Nice.... 

Well, I do like the sound of my 89dB speakers so they stay for now.

@southofdallas  Thanks!

I don't know that hall but I've played in a number of them here in Minnesota (bass in several orchestras so O'Shaughnessy, Orchestra Hall and the Ordway). I know what you're talking about but I'd never have thought to call that 'air'.