@superelmar A lot depends on your room size. When you are using SETs, if you run them past about 20-25% of full power they tend to make more higher ordered harmonics, which, since the power is usually on transients, tends to make the amp sound more 'dynamic'. This is because the ear uses higher ordered harmonics to tell how loud sounds are.
So a typical 300b amp might make about 7 Watts, but it really has a bit less then 2 Watts that are really usable (if you want to hear what the amp can really do).
So my recommendation is to consider an amp with more power. My speakers are 98dB; 2 dB less than yours and my room is not particularly large. I run amps with about 50 Watts; they are loafing most of the time which makes for much lower distortion so greater transparency and smoother sound.
If you are really stuck on using 300bs or 2A3 class A amps, consider something push-pull as they have much higher amounts of usable power, 90% instead of only 20%, owing to far less distortion.
Here's an example of what you might consider:
Raven monoblock
Something else to consider is there are now class D amps that are just as smooth, revealing and involving as the best tube amps.