Tube amps and power consumption

Tube amps and Class A rated amps definitely consume more power. You get what you pay for... I'll take a 300 watt consuming Jadis over a 70 watts consumption Technics any day.

Also, keep in mind that you don't want to leave a tube amp on all of the time. Output tubes are expensive to replace and when on all of the time you will be replacing them at least once a year.

Jadis Orchestra is an excellent amp - just go for it and don't think about power consumption. 300W is not to much ...

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.