A couple of more thoughts tossed out in no particular order.

1) Ever heard somebody say "All amps sound the same." Obvious;y this is not true but the differences in solid state amps can be subtle. However, the differences in tube amps are reported to be significant and obviously the differemce in tube and solid state are large. If I adjust my variable BSC resistor by 1 ohm the sound of the Lowthers can change very audibly. Swapping SS amps in a system probably does not change the damping factor very much and the differences in the system performance are small. Changing tube amps in a system can change the damping factor, meaning the series resistance, significantly and thus the sound of the system is dramatically changed.

2) I doubt that many tube amp designers want audible distortion. I bet that the design goal is to minimize distortion and all audible artifacts in any amp. Obviously nothing is perfect and maybe a tube amp has more of some audible artifact then a SS (or the other way around) but I have to believe that this is not an intentional design goal.

3) If you design your speakers, keeping in mind the amp to be used, I think either type of amp can be made to work very well with a full range driver. In general I believe that speakers designed for SS will not perform well with a lot of tube amps, the opposite is also true in my opinion.

4) The reason I stay with SS is that having essentually unlimited power (>100 watts vs. 2-3 watts) allows me to do anything with a filter or box and still have a working speaker design. Power is not a limitation driving decisions in the design of my speaker system. The amp for all practical purposes is removed from the design. Taking my speakers to somebody else's house (assuming SS amp) produces an expected almost consistent result.

5) If you keep in mind what I have said, you don't have to believe it at all, and go over to AA and read through the High Efficiency and SET forums where people are describing their speaker's performance I think that you will begin to see a trend. The strengths and weaknesses they describe seem to support my observations. How else can changing a tube amp in the system have such a dramatic impact?

Food for thought,

Martin