Streamer always on?

With my Auralic Aries Mini I always sign out of the Lightning DS controller app but leave the device on 24/7 no issues after over a year.

Every audio source except tubes should always be left on
if you want the best SQ. or so I am told.

I’ve never understood the recommendation about leaving things on all the time.  It seems that cooling things off would be a good thing.  I understand it more for tubed gear, because the tubed amps that I have had did take a while to warm up, but then Tube life would be adversely affected, but I also had Tube bias issues with a preamp and it seemed subjectively to me that leaving it on while not playing increased the chances of Tube drift.  When I had an anolog rig I had phono Pre amps that were plagued with hum and ground loops and they absolutely would get louder the longer things were turned on.  Anyway, I now power everything off except my Bluesound Vault2 and two Node2 units.  With Bluesound the units have to be powered up and down as a group or else they won’t play nicely together 

I leave my modified Oppo Sonica on all the time, except I unplug it when doing more critical listening to CD or LP...

I have a 15 year old Velodyne sub and it's never been off, except for power outages.