as to agedhorse's warning about bridged amps and class D amps maybe having Bad Things Happen with DIs in line between the amp and speaker, i think the "tell" is any mono amp with lots of power that won't do 2Ω is likely an internally bridged design.
this brings us back to the idea that there's little point in putting the DI in the speaker line with solid state amps anyway, though. a preamp out will get you all the amp's character at safe levels.
Guitar Repair Gnome
Alpha Music, VA Beach