Yep ,they were worried that the cable would catch fire or something like that because on the 16 ohm tap the voltage would exceed 40V and that's why there's no 16 ohm tap on it.And there also more fuses inside these Canadian heads.
So you want to hookup the load to the jcm800 and then take the attentuated signal and feed that into the jcm900 poweramp section ?I would not go to the front input, it will alter the sound too much.
The 800's,you have to set them loud to get both the preamp and power amp distortion.They don't sound so good at low volumes unless you put a boost in front of it like a TS-9 or an SD-1.
I also have a JCM800 from 81 (so first production year) and I also have the original cab for it with the G12 65 speakers in it.The 65 sounds like the V30 but it doesn't have the highs of the V30.So it's actually a warmer sounding V30 IMO.
gonna prob try to line out of my attenuator into the jcm 900 fx loop return and run a 16ohm cab that way.
the matching cab at the store came with g12t75;s. so i am gonna pass on that.
few things i can do.
use my jcm 900 as a slave.
buy a weber z matcher (cheapest route)
buy another orange 2x12 so i can run 8ohms. rockcrusher has 2 speaker outputs
find an old marshall cab with g12t65. saw 2 for sale locally a few months ago.
i am dying to try out the 65 speaker though. i like the bite and attack on the v30s, but the jcm 800 has a lot highs.
for now, i am stuck using my mesa recto cab.