Speaker impedance patterns - how to read them?

"...My 20wpc Raven Blackhawk not only had no problem driving them to a nice loud level, it made them sound a helluva lot better than a 100wpc ss amp that was also used. Enormously better. So ”
How entirely errrrr ....... Believable ... Not..."

I believe it. Tube amps generally have good power supplies and generous capacitors and they often play much better than the WPC rating suggests. The WPC rating is a guide but it's not the whole story. Yes I know, a watt is a watt but test out enough gear over a lifetime and you will find out that perceived power is not just about watts. 

Thanks russ69. Anyone experienced will know what you are talking about. Not to mention there was about a half a dozen here who heard it. But we are talking Asperger’s-level MDS here. Oh well at least you tried. Thanks again.

I listen to speakers or read reviews of what they sound like and ignore all but a quick look at a couple parameters. I was a former scientist and analytical person who has spent his career doing highly analytical work. I found most the analytical stuff just leads me away from sonic truth. Not wrong to be interested in it… but for me life is too short.

"...Not wrong to be interested in it… but for me life is too short.."

Exactly this. Impedance matching the speakers and amp is more about how they sound rather than having a perfect impedance match on paper.

The question posed by @tomic601 was the exact one Roger Modjeski asked when a potential Music Reference customer inquired about the suitability of one of Roger's amps for use with a given loudspeaker. He advised taking a SPL reading at the preferred listening level, a measurement of the amp's output voltage at that level, then extrapolating the required increased power requirements for every 3dB of added SPL.

I have been conversing with a fellow Eminent Technology LFT-8b owner, who has been marveling about how well his moderately-powered tube amp (I do not recall the amp, but it's under 100w/ch) drives the 83dB sensitivity LFT-8b. That's the same sensitivity as that of Maggies, which require and benefit from a high current amp. Sensitivity alone tells one only so much about a loudspeaker.

Maggies are a nominal 4 ohm load (dropping to 3 ohms at some frequencies), the LFT-8b 8 ohm. And if you bi-amp the ET (the speaker is fitted with dual binding posts, one for the m-p panels the other for the sealed box dynamic woofer), the magnetic-planar drivers present an 11 ohm load to the amp, great for tubes. By the way, the owner prefers the LFT-8b to the Maggie 3.7 he previously owned. The most under appreciated, under-acknowledged loudspeaker on the market. $2499/pr. VPI's Harry Weisfeld declared the LFT-8b to have the best midrange he has ever heard, regardless of price. Yet it continues to be ignored by most. Brooks Berdan chose Eminent Technology as his shops' magnetic-planar loudspeaker.