Does the headphone jack bypass the speaker output or does it still need an 8 ohm load?  If so, can a dummy load be used?  I have a 1960a for my DSL, but this is going in a DI rig I'm building for side gigs specifically so I don't have to carry all that heavy noise.  I know you can't recommend something if it voids the warranty, that's fine.  I'm ripping it out of the cabinet and mounting it to a rack blank so it will be void anyway, I just want to know if it's going to be okay longer term using it like that.  I do have some PC fans I'm going to work into the rack somehow on a different power supply.  Probably one or two for the head internals and one specifically for the heat sink on my dummy load.  Just to be clear, I'm not asking if Marshall approves of this, I'm just asking if it will work in theory.  If that's a no go, then next question: could I use any speaker rated for 100w at 8 ohms or is there a specific type I would need?  Like, if I found a 6" 100w 8ohm speaker that I could just hide in the rack without adding a bunch of weight, that would also be choice.   If the answer to both of those is no, then whom do I need to speak with to get Marshall to make a rack mounted, no cab required version of this head?!

Thanks!