Tube amps and power consumption

One does not normally leave tube amps on all of the time, so the comparison is somewhat moot.

That 70W is only for standby. It can draw much more under demand.

My 100W, class A, SS draws 500W at idle that just goes to heat.

Generally, Class A and Class A/B tube amps will have an efficency in the area of 25 percent. If your amp consumes 300 watts total, then the power rating is around 75 watts per channel.

A solid state Class A is generally less efficient (about 20 percent) even at idle whereas a Class A/B can be 70 percent efficient at idle - a loose term since you're not getting music when the amp is idle - but the power consumption goes up when the amp is pushed out of Class A. This is because the Class A bias is at a very low percentage of the total power.

Everything you stated is par for the technology.

Biasing your JOR will be required about once a year accoridng to your usage. KT 90 output tubes are no longer available, so that you will be using kt88's or 6550's (it won't sound the same as with kt90's). It sounds to me as if you chose a YBA Integra DT (a very nice sounding solid state unit, also French, btw), you might be far better off. See if you can't find one to audition. Happy Listening,

Well judging exclusively from the heat that comes out of my ARC Ref 2 mk 2, tubes use up a lot of energy, fortunately for me I live in Canada so the preamp also acts as a space heater!