Attenuator on MkIV when running 6V6's?

[thindave]

All, I run my MkIVa combo in 6V6 mode (tweed & speaker in the 4ohm jack). If I were to hook up an attenuator to try out (thinking a THD, but open...) would I have to get a 4ohm model?

I'm pretty sure I would but just wanted to check first...

 

[mrmax]

Seems like you would, since the manual says to use the 4 ohm tap when using 6v6's.

 

[thindave]

Thanks. The issue I see with the THD is that if I switch back to 6L6s, I would have to have a separate unit for 8ohm.

Weber has a unit - the Mass - which can switch between a few different ohmages (hey, I made up a word!) - anyone have any experience with it?