Solid state warm up?

It's not the blame that the amp can't drive speakers. Certainly it can, but it's a fact that there are amps that can drive these speakers better than VK250SE and the llist is HUGE even if taken the same budget point.

SS warm up? Tubes yes, SS maybe 15min tops. Your not going to get a dramatic improvement from a warm up. It's probably your setup and the listening room.

I have yet to see a solid state device of any kind that did not benefit from at least 24 hours of warmup.

Certainly in this case its worth a try- if it makes no difference then don't leave it on all the time :) But I think you will find that it does make a difference.

Now- will that fix the mushiness at high volume? Hard to say. If it does not, its probably not because of insufficient power; if a speaker needs more than this amp makes then the speaker is simply impractical for the real world. But if there is not enough filter capacitance in the power supply (or if the filter caps in it are having some issues), mushiness at high volume will be the result, regardless of the power the amp makes or how long it is left on.

Highend4me,

Tubes need only 5...10min to get all DC voltages steady while transistors need at least 25min to reach operating specified parameters.

In fact tubes are not sensitive to temperature at all while transistors are. That's why they need radiators so their temperature does not go above certain point otherwise the power will produce heat instead of current.

It's not fully correct to say that tubes are not sensitive to temperature - generally speaking, they wear out more quickly when run at higher voltages (and thus higher operating temperatures). I presume you were referring to their operating parameters being comparatively insensitive to temperature.