Stan's input is correct as usual. Id offer too you contact the speaker makers and ask them for some input as well.
Youve a few factors in making a good amp to speaker match. The room size. The spl you prefer to listen to. And the type of sound you enjoy
. SET, tubes, SS, Tubes plus SS, etc.
If the speakers are already on hand, one factor is in place. Now optimizing for the room and subjective sound type and volume level is all thats left to address as best one can.. there are tons of info here at the gon in the archives, and online too at various outlets like TAS speaker buying guide.
Design topology isnt predicated to one sort of speaker vs another. Normally. Some low powered, < 100 wpc tubes or SS can push most speakers OK. Even some in the < 50wpc arena can make good sounds. Once you get into the < 20-25wpc arena speaker matching gets way more critical
. If all else is maintained to some degree of reasonableness. In the less than 10wpc
. Or even <5wpc
the speaker selection is incredibly important. As much so with the spweakers numbers as is the type of speaker design. 100+ db speakers dont grow on trees. Each of them has its own voice too
just like the amp does.
IN SET amps like 300b, 845, 211, etc. where amps are only making 3-11wpc, horns are indeed a way to go. Dynamic transducers too can be an option, but their eff has to be way up there. Folks like Coincident, Zu, some Von Schewgert units
and even some hybrid speakers whose bottom ends are self powered now might do ok with flea power.
My last note
figure out which sound you truly truly enjoy
. Then go that way. Ive heard some SET systems I loved and tried to emulate them with other than sET amps
sorry. That didnt work out as planned. But I do like it. Now.
What I want is a SET like sound with the guts & slam of a live reproduction.
Wavelength audio used to have a chart of higher eff speakers online. With some amp suggestions. These primarily revolve around lower powered amps & speaker combos.
There are as well, charts online which will predict the amount of power per speaker eff rating to achieve a certain DB at a certain distance from the speakers. .. this will tell you what you may need by way of the power an amp needs to make in your arrangement and room.