These load boxes from Koch are capable of handling 60 watts continuous and come in compact, tough perforated steel housings, with all the relevant controls and interfaces on one end.
There's a single input for your amp speaker lead, a through jack and a monitor speaker output linked to a three-position level switch. The other common feature is a pair of filter switches that approximate on- or off-axis microphone placement and 1 x 12 or 4 x 12 enclosures.
These feed the recording or PA outputs - the HM (home) version offers an unbalanced standard jack, 3.5mm jack or phono socket, while the ST (studio/PA) boasts a balanced DI output on a three-pin XLR, with a ground-lift switch.
On both boxes the filter switches provided a quick and effective speaker emulation that needed very little extra EQ to sound great in a mix. The PA version's DI is padded down to microphone level (-20dBV); ideal for most stage and studio desks. In all situations, both Dummyboxes perform superbly, transmitting our valve head's complex highs and wide dynamic range with very little alteration and efficient heat dissipation.
The PA version costs more; if it had an unbalanced line-level jack sat next to the XLR we'd have no hesitation in purchasing, but without this, it's a harder choice. The home version will cover any indoor recording situation with ease. Either way, a Dummybox could prove to be indispensable.