Do I NEVER shut it off…?

Up to now, I’ve been following the instructions  and using standby mode if I’m away all day. The amp sounds so amazing on a cold start as well as being on all day… maybe just a little more mellow when warmed up. I’ve only had it a few weeks and only get the weekends to really give it a spin around the block. I feel like the amp is thinking about the music - giving equal measure some of the time…while other times holding back on the boomy bass and articulating clean vibration…at the same time keeping highs like warm honey…never shrill or painful…and presenting this amazing full spectrum of sound that I feel in my nasal passages and my gut at the same time. Slap, Boom & Sizzle… Combined with the SF Serafino’s… I feel like I’m being lured into heaven by Darth Vader who’s been abusing steroids and testosterone and a gorgeous Venice Canal Riva Boat leading me to Cipriani’s for that perfect Bloody Mary…!

Cheers to all for a sound weekend…!

The House reference, was either that one or https://www.youtube.com/watch?v=2JOKakmbnVE  admittedly a close call. 

What, no mention of cartridge warm-up?

i am bothered by two things in your question.  First the assertion that it must be left on constantly. Maybe, but i do not find this to be true with my own designs.  Rather i find a HUGE change in the first 30 minutes, a smaller change int he net hour and a decreasing benefit thereafter -- but your experience my very.
I will say that many of my designs have the low-power circuitry on 24x7 with no provision to be turned on and off - because it does improve sound ( and IMO, longevity).  But the power hungry output stages....my advice would be - experiment and list. Do it multiple times since perception can be affected by many environmental influences. 

My second concern is that it gets marginally too hot to touch.  Maybe i'm just conservative, but that sounds like poor design to me. Nothing i design runs too hot to touch.
Do your own testing.

My brother has the latest Diablo high bias in class A in part he  said shut off and then when listening it may take an hour to fully warn up.