Is it safe to not have a speaker plugged in and used it as a load box?
There's a thread on here where this is discussed. Unless something has changed, the badcat folks say it is safe to run the unleash without a speaker hooked up. However, do not plug a speaker up while the unit is on. I think they said that could potentially damage the speaker.
^Yes the above is correct. Solid state power amps without output transformers have no load requirements...many class D bass heads that are hundreds of watts can be run with no load as simple silent preamps. In fact I have used the Unleashed to allow me to turn up my amp and record direct into Logic without a load...doesn't sound great, but it works and the Unleashed is just fine. I'm looking into possibly picking up some kind of speaker simulator to run with the Unleashed.