Tube vs. Solid State Amplifiers

@earlflynn  Look at the M40.1's impedance.
https://www.stereophile.com/content/harbeth-m401-loudspeaker-measurements
It may be specc'd at 86dB, but the impedance averaged over the whole frequency range is actually well over 8 ohms.

@ejr1953 The Cary Audio link you posted is a general description with some general guidelines for Cary Audio amplifiers. Having owned various Cary tube amps and Cary SS amps both, I can share their solid state amp offering has its own sound signature too compared to other manufacturer SS amplifiers. Each of their tube amps sound different within their line as well.

With a SS amp, you are more pinned down to one sound of that amp. You can play with interconnect and speaker cables to help fine tune it a little more. With tube amps you can alter the sound with different input & output tubes some; while speaker impedance and speaker efficiency becomes more critical. Selecting well matched speakers for a particular tube amp can make a huge difference in how the entire systems sounds. Speaker selection is a key first step and it dictates what type and power level of amps to use in either case if you are looking to achieve a well matched setup.  

Tubes are nothing but power bulbs. Archaic, noisy, additive in distortion artifacts.
Power bulbs hold no mysterious, intangible aura for me. They are plagued by problems. Well executed solid state designs have so many advantages that are too numerous to list. AND SS amplifiers mop the floor with power bulbs in every audible specification and sound quality.

Clearly you have not listened to a HQ tube amp in the last decade or even two.
But you are entitled to your opinion. I have High End Tube Amps and High End SS ( Simaudio, PASS, AR, AH and QS) gear in my home and they are matched with the appropriate Impedance and Sensitivity speakers and they all sound GREAT! Each with their own character and flaws.

But I appreciate them for what they do well and for me it is about the music not the gear. Being an analog guy I prefer valves to SS.
Enjoy the music Earl.

@twoleftears my point is that a 20 watt Raven is not a good match to drive them. Many have attested to this here at this very forum.