Actusreus, I'm gonna jump in with my crude understanding of how the various electronic variables of tube vs SS amps interact with "conventional" dynamic cone speakers.
First, read Ralph Karsten's (Atmasphere's) white paper that discusses the so called Voltage vs Power Paradigms. In short, in the case of SS amps, voltage output remains somewhat constant, but current (amps) vary with the load. That's why SS amps can increase wattage when driving low impedance speakers, particulalrly in the low bass region. As impedance drops, power (watts) increase.
Not so for tube amps. In the case involving typical tube amps, current (amps) remains relatively constant regardless of impedance, but voltage varies. As a result, power (watts) doesn't change as much over the frequency range where impedance changes all over the place.
My ARC tube amp power rating is pretty constant regardless of impedance load, which is consistent with the Power Paradigm as described in Ralph's white paper.
Another difference is damping factor. SS amps generally have higher DFs than tube amps because SS amps generally have much lower output impedance factors than tube amps. I think DF is calculated as: speaker impedance/amp output impedance. Ralph and Al have written that much ado has been written about DF, and the bottom line is that it is a misunderstood and over-rated stat. The "lure of the law" so to speak is that the higher the DF, the better ontrol the amp will have over the woofers. The short answer is not necessarily.
My tube amp has a DF of 8. Yet it has great bass slam and extension. Why?? I have no idea.
I'm still waiting for a cogent response to a question that I posted in another thread which is how can one make an informed choice between mathcing a particular amp with a particular speaker. I still don't know. All I DO know is that I am satisfied with the sonic swill coming out of my speakers even even though I'm dumb as a stone.
Hope this helps.
Happy Holidays,
Bruce
