Ok, first off, yes I own the MEGA DUMP. Secondly (@ miche), no you don't have to put your cab after it. The attentuator basically "harnesses" the output of the amp, so it makes the dummy load. You can either hook up a cab, and attentuate the level of the amplifier output, or have the output of the attentuator go straight to your DAW for a "line output" to use speaker impulses on.
The thing you have to understand is that without a load (either dummy or actual speaker cabinet) being placed in the output path of the amplfier, the power will be looped around in the amp. Basically. So if you have, for instance, a 5150 or XSr, then you have 120w of output being looped around and around
inside the amp. This is what causes transformers/tubes/fuses/etc. to blow up. With a power attentuator, i.e. dummy load, or a speaker cab, that 120w is being fed into something and released, therefore not being looped around inside the head. When using a power attentuator, then, no you don't need to have the cab hooked up, because the HotPlate/PowerBrake/MEGADUMP that you are using is taking care of that end of business for you.
@ Atheist - I am using interfaces that have instrument inputs, which basically
are the same thing as a DI box. I've never used the FX Loop SEND into anything without an instrument input, so I don't know if a DI box is needed, to be honest.
@ kaomao - I was turned on to Weber products by DSS3, and I ordered one soon after him telling me about their products. I'm extremely happy with my MEGA DUMP, and we actually use to rent a HotPlate religiously from a place here for the purpose of getting cranked tone at lower volumes. The WEBER does the same thing, but can handle all OHM loads in one unit, has some eq options on a couple of models which help tremendously because using attentuation the eq of the sound is different..., costs half as much, and is just as reliable. The thing with the THD products is they are advertised much more..in fact I've never seen a Weber advertisement. Please don't correlate advertisement/mainstream with reliability and quality, it just costs you more in the end man
~e.a