Zyx Universe. O.24 mv vs .48 mv with low eff spkrs

Efficiency is pretty important if you want tube power, as tube amplifier power is more expensive. It also does not pay to work your amplifier hard regardless of the amplifier, not if you want to hear the best the amp has to offer.

In my room with speakers of this efficiency I would need over 1000 watts!

I might make a recommendation- talk to Duke at Audiokinesis. He makes reasonably priced loudspeakers that are extremely musical, and also easy to drive with most tube amplifiers. This will solve your sensitivity issues with the preamp and phono cartridge at the same time.

My guess is that once you hear the Atma amps w a suitable speaker, your only argument will be w yourself, for not doing it sooner. IMO, the Salk speakers are beautiful, real craftmanship, but clearly designed for high power SS amps. A high(er)/flat impedance, high(er) efficiency speaker designed for tube amps is the way to go w the Atma amps. My own experience is that you do have to be somewhat concerned about hum and noise when you go to very high eff speakers; the higher eff the more careful you have to be; there's a reason why many low power amps (likely to be mated w high eff speakers) have hum pots!

Swampwalker, I am guessing you've not heard our amps in a while! At the Munich show we did not use the jumper plugs as described on our website, yet to hear any artifact from the electronics at all, you had to have your head inside the horn of the loudspeaker, which was 107 db. Even then it was a gentle hiss.

The speakers at the Munich show were Hornfabrik:

http://my-hiend.com/leoyeh2/2014b/IMG_3428ss.jpg

Lewm, the big problem on horns usually is not the noise of the amp but the noise of the preamp. If you knock the gain down in the power amp you thus make big strides in reducing the noise floor.