Debate: Class D amps need 48 hours of warmup

Over the years, I've found that all my power amps sound less harsh or lifeless after 30 minutes of warming up. More so my old B&K class A/B amps, but less so with my current Peachtree GAN-400 class D power amp which seems to sound open after only 10-15 minutes. Not sure if this has anything to do with the GAN topology... Since I like to listen when the mood strikes me, I like to keep the entire system including the power amps powered on 24/7 save for extended vacations and lightning storms.

My hybrid (class D and tubes) PS Audio M1200 monoblocks sound their best after ten minutes of playing music. Really interesting to hear how the sound improves during those first ten minutes of getting warmed up.

When I inquired specifically, my current amp Vendor (Class D Audio) instructed  to turn mine off when not using. It always sounds fine then when turned on to use.  I always left my prior amps on in the past. I also cannot say I noticed any burn in period with this amp ie it sounded fine right out of the gate.  I will say when I heard my first Class D amps (pre-owned Bel Canto ref1000m) many years ago,  it was my ears that had to totally adapt to the dramatic change in sound (for the better by far). YMMV. I would say this is a case where you have to try and see unless there is clear evidence pertaining to your specific amp that can be  banked on. 

In short, the amount of time is not important.  At the component level, especially IC's, there are behavioral differences caused by temperature.  If you experienced a difference after a 48-hour warmup, it was simply due to the difference in temperature between the two times you listened, your blood pressure, mood, what-have-you. 

I turn my Hypex powered Marantz integrated off overnight during unsettled weather. About 20 minutes after turn-on, it’s back to peak.

When I had an all-tube Cary SLI-80, it would take 45 minutes to an hour to sound its best.

Then there was the class A Pass Aleph. If it was shut off for more than a couple of hours, it wouldn’t sound its best til the next day!