If you are more use to to the dynamics of your SS or Class D amps driving your 98db efficiency speakers, it could be quite an initial change to your ears dropping to one of the 2-4w single ended amps suggested here. It's not that you won't like it, for awareness, it is going to sound different, likely more billowy and plush and less punchy and dynamic comparatively to the amps you've tried so far.
imo, the key here is trying a few different amps with your speakers. The recommendation to demo a few amps a with return policy might be worthwhile so you dont get stuck with something you don't like, and/or allowing the amp merry-go-round to continue through two or three more tube amps to get closer to what you are looking for.
There are some tube amps that sound very close to solid state amps, clear, dynamic, yet lacking tubey characteristics you might be after - so its worth figuring out how to try a few different integrated tube amps or a separate tube preamp and separate tube amplifiers to match with your speakers. Or, maybe end up with a handful of different low watt single ended and higher power push pull amps in your stable for a while to try and narrow down different results and sounds you like more. I find taste varies from one person to the next about what sounds good to them.
What impedance are your 98db speakers (4,6,8,16 ohm) etc?