FWIW I have some 4ohm speakers which I have driven with 4 different tube amps, a 35wt integrated, a 60wt triode, an 80wt pentode and a 160wt pentode. The speakers have 2 woofers, 2 midranges, and a tweeter. They are ported. They have an efficiency spec of 92db. The larger amps drive these speakers with ease at volume levels that can overload the room at 4 or 8 ohms. The smaller amp has the same capacity, volume wise, but for some reason do not sound as smooth in the mids/highs off the 4 ohm tap, which you would think the speakers should be connected, although the bass is just fine. Off the 8 ohm tap they are much smoother but the bass is just a tad soft, a little of the impact gone, but very little.
The point of all this is that some extra power can go a long way, that is the larger amps can drive the speakers better throughout the frequency range even though none of them is really max'ed out power wise. The 4 ohm speakers sound fine on the larger amps on the 8 ohm taps - as with the smaller amp the highs seem smoother. I suspect that the larger ones just have better transformers and can drive the woofers better even at a higher impedence.
Hope this helps some in your decision. FWIW 100 watts of tube power is a lot of power!
The point of all this is that some extra power can go a long way, that is the larger amps can drive the speakers better throughout the frequency range even though none of them is really max'ed out power wise. The 4 ohm speakers sound fine on the larger amps on the 8 ohm taps - as with the smaller amp the highs seem smoother. I suspect that the larger ones just have better transformers and can drive the woofers better even at a higher impedence.
Hope this helps some in your decision. FWIW 100 watts of tube power is a lot of power!