I have a lowdown 400 HD. I am looking to change to light weight cabs. Am I correct that as long as I am running 2 x 8ohm cabs the amplifier will put out no more than 400W RMS so I could use 2 x 200W cabs and not blow them? The cabs I have in mind are actually TC electronics at 250W each so there would be a little head room.
Yes, you can use those cabinets. When you're using both cabinets at 8ohm, your head sends 200W to each cabinet.