In a 100 Watt amp which usually has 4 valves you can halve the power to 50W by switching off 2 valves. You can even just take a pair of valves out if your amp doesn't have a switch, but you have to make sure it's the correct pair, and, you may have to change the impedance output you connect the speakers to as you've increased the impedance of the
valve power stage. Hopefully the switch will do this fo you. There is some debate as to what you should do if you don't have a switch, so I leave things as they are.
Further reductions in power are achieved by changing the operation of the valves from triode to pentode, again giving about half, so with just 2 valves and triode node you're probably down to 20W.
If you change the output to use one valve in class A then you're probably halving again for the single valve and half again for the class A so this will take you to maybe 5W!
Most amps dont give you all options (thank heavens)!
As for bedroom levels, I use a 100W amp with a master volume for practice (louder than bedroom, sure) and it sounds ok turned down. Or you can get a power soak/attenuator connected between the amp and speaker, this will mean the valves are working at their best but only a small signal gets passed on to the speaker reducing volume.
Jim
