calling all Guru;s, Ideas on audiophyle high effeiciency speakers solicited

Wanting to enter the "Tube system" realm. After extensive research I've come to realize that my current low efficiency speakers B&W 803D2 require a lot of power and may not cut the mustard using tube gear. Although I truly love the speakers I may end up swapping them out in the future to accommodate my new found rabbit hole. Tube amps in general provide only minimal power certainly not enough for my listening habits. 
Anyway what , by any standard, constitutes a high efficiency speaker? is it a rating of 80....... 90, 92,......97? just what is it. Do speaker manufacturers fudge the number on occasions? How do we know? Is a 2 way design inherently more efficient than a 3 way? Does  the amount of speakers in a cabinet affect efficiency?
Last of all what are some audiophile grade speakers? 
You either truly love your speakers, or you don’t. Loving your speakers says you are happy with the amplification driving them, as you are listening to the combo. Are you really happy ?
Not listening to the combo yet. Soon I hope but not yet. Currently not happy with my amplification into the 803s Adcom 555II that I had to pull out of retirement after my Krell KAV decided to take a permanent vacation. Thats when the tube bug bit me. Tube amps may not be powerful enough to drive the 803s into nirvana
How did you feel when the Krell worked ? I do not feel tubes are a match with your speakers.
Loved the sound with the Krell, would not mind trying a more efficient speaker with a tube sys but need to know what to look for

You're speakers allegedly have 90db sensitivity with a nominal impedance of 8 ohms. In theory, that's fairly efficient by today's standards, and should work with a tube amp of about 50 watts. After all, B&W recommends a minimum of 50 watts. However, it seems most B&W owners end up settling with powerful SS amps. 

If you want to try tubes with your B&Ws, I have no doubt that a Rogue Audio Cronus Magnum will drive them to sane volumes. That's about the most glass power one can get for the money. If your heart is set on low power SET amps, you'll need different speakers, ideally some of 94db sensitivity or greater.

 Some will tell you that tubes necessitate 3-digit sensitivity. That's complete rubbish. I can drive my 87db spec speakers to loud volumes with 45 tube watts. Also, room gain, listening distance, music genres, particular amp design, and desired headroom play a significant role.
Contrary to untutored belief tubes are NOT inherently better than transistors! I own many amps of both types! Your 803D2's are truly excellent speakers and capable of better sound than ANY high-sensitivity types. I can recommend a New York Audio Labs NYAL Moscode 300 (tube/MOSFET hybrid) to power the B&W's. A superb amp designed by George Kaye - and capable of handling difficult loads! And being a hybrid it will give you a nice taste of tube sound - without the drawbacks of an all-tube amp!
I can speak from experience, owning a NYAL Moscode 150 (half the power of the 300)!
High eff is over 100db medium about 90+db up ohm load also effects ability to drive and must be considered. Most high eff designs use large cone area many need to be multiway over 3-5 way depending on end goal and range required. I would suggest you select tube amp maybe list budget system room and over all system goal you wish to achieve if you want more detailed information. I would say pursuing higher efficiency can be a laudable goal and can yield incredible sound over conventional systems but users need to have a bit more knowledge when selecting such over what one needs for standard audio fare.
@gillatgh - There may be no need to sell your speakers...

Take a look at this web site and contact Pete McAllister for his opinion on whether he has an amp that will drive your speakers.

He may also share his thoughts on your speakers, but remember -  it is only his opinion :-)

Search this forum for feedback - there are mostly positive and some negative comments - it really depends on your taste

He has an amp for most purposes - including monoblocks rated at 195 watts per channel - loud enough? :-)

His amps (all tube) are very articulate and detailed with extremely good dynamic response and imaging

The only drawback is - he builds everything himself - including hand winding all transformers, so they can take a while to build (2-3 months) - but his amps will last you a lifetime.

A friend has had one of his amps for 40 years and it still sounds amazing

If you have to sell your speakers take a look at Tannoy speakers - the DC10A springs to mind - Pete may try to convince you to look at  Electrostatics (not everyone's tase) but his amps do work well with them

Good luck with your quest - Steve
Thanks and shout out to all who took time to read and answer my thread. I appreciate all your responses and am gaining knowledge which I was seeking. Thanks!
Having ordered a Rogue Pharaoh  hybrid Integrated recently, spur of the moment I then realized that I might have a problem. Hence the thread. The Pharaoh is combining a tube Pre with a SS class D amp rated at 185W 8 ohm and 350W 4 ohm, no 2 ohm rating given. I'm really hoping that the 185W will be sufficient to drive the B&Ws at my sometimes listening levels 85 - 95db but sometimes at a little higher at 100db as measured on my Radioshack SPL meter. Never more than 100 (occurs when really partying down hard). Rare occasion indeed!
There’s a Krell KSA 300s up for sale right now that you may want to consider given your listening habit and previous fondness for the brand. You may just need a floor jack if you need to move it around the room.
Is your SPL meter measuring with "C" weighting?

Most quality 4 ohm amps can handle 2 ohm impedance dips. The Rogue will be fine in that regard. From personal experience with that amp, I can tell you that it doesn’t sound anything like a full tube design, even with vintage 12AU7s. It seems many buy these (and the Sphinx) amps thinking they’ll get the best of both worlds: high damping factor and power combined with a lush and 3-dimensional midrange for which tubes are known. I’m sorry to say that is not the case. These hybrids merely sound like other Hypex class D amps. But not only do they not emulate a true tube amp, they don’t possess the impressive bass depth and heft of a good SS design. Compare one, level-matched, at about 70db to any decent class AB amp and you’ll notice a huge disparity in bass extension. However, if driving your speakers to high SPLs without clipping is your goal, they’ll do just fine.

I’ve also had the Rogue Audio Cronus Magnum II. I was surprised by how much it outperforms the hybrids in every respect, partly because a Rogue employee suggested I buy the Pharaoh.

In fact, my performance ranking for their integrateds: Pharaoh < Sphinx V2 < CMII.
Yup, I actually preferred the Sphinx to the Pharaoh. Its soundstage wasn’t as wide but it was better balanced and actually seemed more powerful.

Use the Pharaoh in your system for a while so you can truly appreciate a real tube amp when you finally take the plunge.
I had a Cronus Magnum II with the KT120 tubes.  I changed out the 5 signal tubes but never got it to sound that great.  At 2500, it is a lot power for the money but there was a certain grainey sound I could never warm up to.  I sold it  pretty quickly.
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yes C weighted use it consistently throughout my listening excursions. It actually rarely gets to 85db but there are those times when........,? since I'm already committed I'll do some serious evaluation of the combo and post my results the forum. That's not going to be anytime soon. I like to give things time to settle before jumping to conclusions.