Marshall Power Brake -- how to use headphones

[RustyBrooks]

Hi Guys,

I recently purchased a Marshall Power Brake, which I use as an attenuator to be able to crank up the amp to get a decent saturated tube tone, without making a lot of noise.
This works pretty good, but even so, with my 60 watt amp, it's too loud at the highest volumes, by far. I shudder to think how loud it would be without the power brake.

Someone has mentioned before (not here, elsewhere) that when the attenuator is at the lower level (-30dB) you might be able to run it into a preamp or headphones, i.e. use it as sort of a line out.

This does, but does not, work. If I just plug in headphones to the power brakes output , I get no sound. If I plug in headphones and lead the other output to the combo's speaker input, then I get sound in both. I'm assuming that the power brake simple doesn't "turn on" the outputs unless they have a low-enough impedance. And headphones and preamps in general are going to have high input impedances. Does this sound reasonable?

So, is there some way to get a line-out of a power brake? Some device that has the right input impedance and a headphone out? Would it be damaging if I rigged together or bought a dummy load, and plugged that into the first power brake output (to enable output with an 8ohm load) and plugged the headphones into the other jack?

If that doesn't work I'm going to break down and build either a speaker isolation cabinet for the amp, or a custom isolation cabinet for a single speaker, in either case, It'll be expensive, I'll need mics, mic preamps, maybe more eqs and compressors, etc.

I just want something where I can experiment with headphones without disturbing my neighbors. Maybe I should just buy a house.