Are these speakers fully compatible?

I'm not sure which JohnBlue speakers you're looking at, or how large a space you would be using them in, but I have a pair of JB3's and drive them with a 10 watt EL84 amp. Mine are in an office setting and the 10 watts drives them easily. The sound is exceptional from such a small rig, as well. I'm very happy with the combination.

For quiet listening it will be fine. Going to 90db won't get much of an increase. 87db to 90db will double the power but it takes 10db to double the perceived volume. I'd look at 93db or better if you want to "rock".

Currently I have a 7 watt amp that drives 88db speakers fine. However, it really sings with my 94db speakers.

So, you have apprx. 3 wpc of clean power.Alas apprx. 4 db = 91db (87+4db's) of clean output from the driver/s. Can you get by on peaks of 92=92.5db of peak output.
Personally I can almost get by with that but, I have found
that most, NOT all, audiophiles ears are no longer sensitive enough for this to be adequate. As always YMMV.

I'm not following Harley52's math, but I found that a 300b was fine w 89 dB speakers in a medium sized room (14 x 23 x 8.5 = 2735 cu. ft.) if I wasn't pushing them to high spls. If your room is truly small (12 x 12 x 7.5 = 1080 cu. ft, which means my room is 2.5X bigger)), I would imagine that the combination would be adequate, unless you wanted to try to play back large scale classical or hard rock at high spls. One advantage of tubes is that they generally clip much more gracefully than ss.