Koch Amps LB120-II/8

Sorry, my german is a bit rusty, so here it is in english. It does what it says it does and does not alter the tone while at it. Beware that this thing might not necessarily help you get a bedroom level sound. The 1% attenuation level from my 50 watt Marshall JVM is 0.5 W, which can be loud as hell.

The XLR-out with the speaker emulator is a godsend. A bit sterile and lacking actual speaker characteristics (when compared to, say, vintage 30's), but still does the trick and very nicely. Using that you can crank up the master volume and really let the amp sing. Recorded tunes via XLR sound good, so I guess in a live gig the LoadBox could also be effectively used for miking.
The only thing that could have been better is the headphone output. This is really sub-par and does not bear any criticism. It's fizzy and it literally hurts your ears. Don't let this stop you from buying the LoadBox, though. Just get a headphone amp and plug it into the line level output. For late night practicing that option works like a charm.

It does not seem to require any additional cooling, with a 50W amp at least. Stays cool even after hours of abuse. Other than the headphone out, this gadget is a perfect addition to anyone with a tube amp.