Need some Amp help - a little new to properly powering speakers

You do not need more efficient speakers for more detail. The most detailed speakers may well be Quad electrostats, and they are horribly ineffcient.

The first statement is true, the second is partially false. Quads are planar loudspeakers, and so the 1 meter measurement does not give their true efficiency. In general you can add 6 db to the measured figure and be a lot closer to their actual efficiency. This is true with any planar. 

Al, If a tube amp were used on this speaker, it would probably do fine if used on the 4 ohm tap and if also running about 20 db of feedback. The impedance curve would then present no worries.

I only mentioned a tube amps simply because the OP is dealing with a lower volume loss of detail. Low level detail is something that tubes can do considerably better than transistors. IMO this has to do with the linearity of the devices themselves; even pentodes are not that bad at lower power levels.

@kosst,

You completely misread my post. I was speaking of low-volume dynamics. I don’t know how you confused my statement unless you simply read it too fast. This is what I said,

His original post stated that he noticed a lot of "imaging" loss at lower levels. Maybe he was referring to imaging in the true sense of the word, but I’m betting that dynamics is the more appropriate adjective. I’ve never had an issue with low-level imaging, but all mid-efficiency speakers I’ve owned struggled to produce decent dynamics under 70db

Since you mentioned LS50s, I happen to own a pair, and they, like other low efficiency speakers, have weak dynamics at low volumes. It doesn’t matter if one feeds them tube, SS, class A, or AB power, nor does high or low damping factor make a difference. They simply need a certain level of voltage to open up and that means louder volume.

Anyway, the OP subsequently confirmed what I suspected, that he was actually referring to dynamics, not detail or imaging.

What folks here seem to fail to comprehend is that many listeners want the same "jump" factor (mostly regarding bass) at low volume that they get at higher (80db+) volumes. Amp manufacturers began to compensate for this with "loudness" controls once low efficiency speakers became the norm. Then the movement toward minimalism and home theater came about. AVR manufacturers know that most will only use these products for home theater, so inclusion of a loudness control is no longer worthwhile. The boutique minimalists swear that any such control compromises the sound, and/or the BOM for the rest of the amp. That leaves one the option of using separate DSP, an EQ, or high efficiency speakers to attempt to compensate for the loss of low-level dynamics.

Any honest speaker designer will attest that high efficiency speakers produce superior dynamics at low volume. I know you don’t like to read that based on the speakers you own, but it’s the reality.

I own both high and low efficiency speakers. I don’t consider either approach inherently superior. Each approach has strengths and weaknesses.

I would only suggest 30 watts if the OP only listened to polite music and only listened at polite volumes. I couldn't find measurements on this specific speaker, but another in the range dips to 4 ohm with a -47 degree phase angle. I would expect the larger speaker to be more challenging to drive. That, combined with the lack of sensitivity, would make me consider a bit more power than 30 watts. My 32 watt amp is just barely competent to power my 92dB sensitive Focals and I'm certain I drive that into class AB on a regular basis. 

Hi Al,
 Thanks for the additional specifications,  I was relying on information from the Polk website. "If"  the tube amplifier has good quality transformers and power supply (PS) I feel the same as atmasphere.  This type of tube amplifier using its 4 ohm tap has a very reasonable chance of success. Atmasphere's recommendation for about 20 db of NFB (or thereabouts) makes sense as this would lower output impedance and conversely increase the DF (Damping factor). 

Meeting this criteria and the need for quality transformers/PS is the challenge for the stated budget for such a tube amplifier. 
Charles 

30 watts was a minimal recommendation to provide moderate/reasonable listening levels. All 30 watt amplifiers aren’t created equally. There is a hierarchy of quality that definitely exists. For example I would be confident that the VAC Renaissance 30/30 amplifier (excellent output transformers and PS) could drive this speaker from its 4 ohm tap and produce beautiful music while doing so. Problem is you won’t find a used one anywhere near 1K dollars. A used Cayin, Line Magnetic or Quicksilver in the 50 watt range push pull class A/B would work pretty well I believe. Interesting thread.
Charles