To turn off or not to turn off

That is to be correct and I even more verified that SS equipment idles at very low power and need not to be turned off unless there's threats from power surges. Tube equipment is the best to turn off since the worm-up time is much faster than with transistors.
On my VTLs tube life drammatically increased since I started to turn them off. I would turn off the power especially when I leave or to the degree that I would only run them on when I play music. When something's happening I would immediately hear and take actions on time. Despite the figures stating that tube life won't be different if tube equipment is always on, the life of DC capacitors will be and the ones that go bad or off the normal operation scale will shorten the tube life so quick that it's enough to realize that buying more and more tubes becomes an issue. I'm speaking from my own experience with my tube amps that I analytically examined with open PCB what's realy happening and why my tubes blow so fast... As I mentioned above, DC caps in some tubes drained the voltage too low outside of bias adjustment tolerance or too high and after some time of idling biasing was not possible. In the result I recapped the units and NO MORE I keep them on without listening.

You can get a Kill-a-watt and see how much energy your equipment draws. It may be illuminating. As for the cost of leaving equipment on, you can compute the draw from your rate schedule, usually published in your utility bill. 60W x 24 hours x 30 days = 43200 watt/hours or 43.2 kW/hours. Here in southern California, the summer rate at worst case (301%+ of baseline) adds up to about 42 cents per kW/h. That is over $18. My Gryphon amps used to draw 500W each at idle; my Lamms drew 300 x 2. My bill was scary plus I was probably using up a lot of water (if a coal plant) which is bad news as we have a water problem as it is.

I have no idea what my carbon footprint is but I imagine it is not good, which is why I try to keep things off, use energy saving light bulbs, turn off lights in rooms I am not in (which is what I learned as a kid).

I have even tried LED bulbs - they work okay but now that two have died before 100,000 hours (or since I have 5, stochastically, 20,000 hours, which is not, however 4 months) at $30 a pop, they are a no go.

All of which is to say that stereo gear can easily cost $50/month or more just on idle. The Lamm pair of amps alone would cost $180 to leave on all day (600W constant).

I do leave my current setup on standby and can stand the $30 or so it costs me for the privilege.

"SS equipment idles at very low power and need not to be turned off unless there's threats from power surges." UNLESS that SS gear happens to run in Class A.