Maybe? There certainly could also be longevity/reliability benefits of reducing power cycles. Mostly for the power switch I would guess. (Thank God for the triac mod that saves the power switches on vintage gear.)

I’m mostly saying there are no sonic benefits to leaving it on.

No. There are benefits in turning it off – it offers some protection from voltage spikes and from premature aging of the circuitry, and saves electricity. It may offer protection from someone messing with the speaker wires and creating a short when you’re not around.

I design electronics. Any decent modern amp or preamp is electrically warmed up in tens of seconds, that is, further changes in temperature don’t make any meaningful difference in its performance – measured or heard.

Really ancient stuff? There could be a kernel of truth. Tubes have heaters that take time to warm up of course. Ancient solid state (like early '70s and before) sometimes had janky bias spreader circuits that weren’t well compensated for temperature.

In newer solid state gear, the output stage bias current should be within 20% of the final level within tens of seconds after power on. There’s enough feedback around the output stage that you’re not going to hear any difference while it stabilizes, and it stabilizes pretty fast, much faster than the temperature of the heatsink settles at its final level.

Don’t worry about warm up. Worry about what happens to your powered up gear when you’re asleep or away.

Running out of voltage is harmless – the amp clips, it sounds bad, you turn the volume down, and life goes on. (The ostensible purpose of level meters is to help avoid clipping but we all know they just look cool.)

Running out of current can damage an amplifier. It can overstress the output devices and damage them, maybe catastrophically.

Fancy amplifiers have circuitry to protect against this, either nicely by momentarily reducing volume, or crudely by cutting off current output. The latter causes the amplifier’s output to momentarily present a high impedance to the speaker. That sounds bad and might damage tweeters, if flyback current from a moving woofer ends up in the tweeter since it can’t return to the amp.

Bob Cordell has a chapter in his amplifier book where he talks about how you don’t really need the protection circuitry. If the amp’s output stage has enough current capacity it becomes impossible to overstress it with a speaker of a given impedance.

My rule of thumb based on Mr. Cordell’s math is: if an amplifier has one pair of output transistors per 50W rated power into 8 ohms, it can safely drive any 4-ohm-rated speaker (regardless of its demand phase curve!) and will never be overstressed. Note this assumes dynamic speakers, not electrostatics.

For example if an amplifier is rated 150wpc @ 8 ohms, and it has 3 pairs of output devices per channel, it’s safe to drive a 4 ohm speaker. But if it only has two pairs of outputs, you’re on thin ice. (And you could double that number of output devices if you want to be safe into nominally 2 ohm loads, or halve it if you only care about nominally 8 ohm loads.)

I had the similar STR GX9ES for a while. Nice clean sound.

5Gbps can transmit the entire contents of a compact disc in about one second. I’m not watching the vid but hopefully they got that point across.

It’s a 0.35% THD amplifier. That’s 3500ppm.

This is not a good amplifier.

Reviews are bullshit mostly. The manufacturers, hifi dealers, and review rags are cozy with each other.

Specs are real. For amps and preamps, the distortion and noise spec is your best predictor of whether it’s gonna sound clean or have “character.” Another spec that matters is stability margins which no manufacturer publishes, sadly.

Likewise the efficiency and frequency response spec on a speaker tells a lot of the story. Directivity also matters but I don’t think we have standardized metrics for it.

Two channels is a better value than multichannel.

Floor standing full range speakers are a better value than lil fellas on stands.

Read the specs. Distortion specs for an amp tell you if the designer was paying attention.

I don’t really think integrated amps or receivers are a better value than separates. Over a long period of time you’ll accumulate various electronics and you’ll have a favorite preamp and a favorite power amp. It’ll be simpler if your favorites can be matched up without having to explain to family why there are two volume knobs and only one works! and you can sell all the hardware you don’t end up using.

Wear ear protection when working with power tools etc.

You don’t need fancy cables. Plain copper wire for speakers, simple shielded RCA for interconnect, any damn thing for AC power.