Thanks a lot to both of you. I suspected as much, but i had to be 100% sure before i blow anything to pieces
.
As for the math;
---7--\___6_
---7--/
6+[1/(1/7+1/7)]=9.5 ohms.
This is great news. Hopefully i'll have some cab building tips, as well as a brand new physically-deranged cabinet in a couple of weeks.
and garww; I'm aware of the impedance changing as i'm playing, especially considering there's a tube inside. I just don't know how the amp will react.
Putting the amp out on the market with a 6 ohm speaker sounds risky, at best - hence my doubts.
I like your downhill-freewheeling analogy, nonetheless. Gives εR a whole new meaning by the time the ambulance picks you up.
(I suppose ε-Ir=medical bill?)
Again, thanks to both of you for your help!