Amp warm-up and the merits of keeping gear fired up

I brought home a used Burson Soloist HP amp, fit it on my rack, powered it up and immediately began listening to a familiar CD. Amazing the detectable swings it went through from cold. First sloppy, sweepy highs with prominent mids.  Next the mids gained balance with the bottom girth growing. With more time the highs got right while the bottom end gained correct presence. Took about 30 minutes before the sound really settled.

This from a HP amp noted for its minimal parts. The rest of my system had been on constant power. Consider the more massive transformer and capacitors on the big gear and it's no wonder prevailing wisdom is to keep gear powered up. Add to that consideration for on/off cycling taxing the capacitors longevity.

While the HP amp may be the lowest power draw in a given system, it might also be the most sensitive to a cold start.