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

So they're actually just 81db efficient when stated with industry standard specs? Ouch.

Very good discussion here and with wise opinions.
Syntax, your heavy/light car analogy for high/low efficiency speakers is a excellent illustration. I've never understood the prevalence of inefficient difficult to drive speaker that require behemoth amplification. This results in poorer sound quality in my opinion. In this case the Salk-Atmasphere isn't a good pairing, one or the other has to go.High End audio moved away from high efficient-high impedance speakers a couple of generations ago. This was a wrong turn and not a good direction to follow.
Charles,

05-21-14: Dougdeacon
So they're actually just 81db efficient when stated with industry standard specs? Ouch.

Doug, "industry standard" is probably ambiguous in this context these days, as specifying speaker SPLs relative to an input of 2.83 volts rather than 1 watt is pretty common. Measurements presented in reviews often do that as well.

For an 8 ohm speaker (that is really 8 ohms) it makes no difference, as 2.83 volts into 8 ohms corresponds to 1 watt. But 2.83 volts into a 4 ohm speaker corresponds to 2 watts, which results in the SPL number being 3 db higher if the input is 2.83 volts rather than 1 watt.

Since a high quality solid state amp will usually approach or equal being able to supply 3 db more (twice as much) power into 4 ohms than into 8 ohms, specifying relative to 2.83 volts arguably has a somewhat reasonable basis. But tube amps can't do that, of course, so the 2.83 volt "specmanship" can be particularly misleading when a tube amp is paired with a low impedance speaker.

Best regards,
-- Al

If you are married to those speakers, I agree with all the others; you need to select a different amplifier. As a long time Atma-sphere devotee, I would instead choose a speaker better suited to the amplifier. For me, I don't know which came first, because I have been listening to OTLs driving ESLs all my audio life, as a matter of preference. If you should choose to switch to Sound Lab ESLs, I have many useful ways in which to improve dramatically the match between an Atma amp and an SL speaker. In this case, the word "dramatically" is an under-statement, not an exaggeration. I am driving my Sound Lab 845PXs with my highly modified Atma OTL amplifiers, but the modified speaker can be driven to very loud levels by ANY 50W tube amplifier, after modification. In addition to a vast upgrade in efficiency, the modifications also increase the impedance across most of the audio band, not less than 20 ohms from 50Hz to 5kHz. A win-win. Just let me know if you want input on that subject.

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.