Please Recommend Highly Efficient Floor Standing Non-Horn Speaker Suggestions

Just adding my humble 2 cents.

if you don’t mind dipping slightly below to 89dB sensitivity, take a look at the Kharma CRM 3.2 FE or their similar models. The 3.2 was reportedly voiced with a pair of single ended Lamm ML2. Just prepare to feed it with high quality front end because thats the only way to extract the best from these speakers. They are extremely revealing. Speaker load is very easy with tube friendly phase and impedance.

The 3.2 throws a very natural soundstage as deep and wide as your recording allows. Image is rock sold and believable is a smooth analog manner. This is one of the few speaker I have the pleasure to own that doesn’t need room correction and sound completely uncolored. I have no problem driving them with a pair of 90 Watts Class A to reasonable loud levels.

FWIW...The MC275 will drive my Focal Kanta No.2s just fine and they are rated at 91dB. Since they tend to drop to less than 3 ohms at 105Hz the 4-ohm taps are often preferred. 

+1 for NSMT Model 50. 100 dB. I've used with 45, 2A3, 300B, First Watt M2 

If you want to use very low power tube amps there are only a few choices that are not horn speakers.

In my system the Luxman MB-3045 tube amps at about 60 wpc are an excellent match for the ProAc Response D-40r (90db)

+1 kanta 2 or 3