Vac Sig MKII tube circuit upgrade

I believe Drummermitchell is right about this.

04-11-12: Drummermitchell
I believe just the MKII as the IIA has that tube swap option installed already.
Drummermitchell (Threads | Answers | This Thread)

Not true. Only the later Sig MKIIa has the tube swap option. I ordered my Sig MKIIa in mid 2011 and it has the option.

I spoke with Kevin and there's no circuit change, just a switch out of the signal path to deliver 6.3 or 12.6 volts depending on the tube type.

I hear the IIA is going to get a stellar review in next months issue of the Absolute Sound.

Must have understood Vac's website.
The earlier II and IIa can be upgraded so a user can swap out
different tube types.

Knghifi,don't suppose you have been experimenting with different tube types by chance,any thoughts on the extra possibilities.

My Phi Beta preamp has the switchable option of using 6922 or 8416. I briefly listened to one of my favorite 6922 tubes, Hamburg Valvo Red Labels from the early '60s. I like this tube's combination of body, clarity, and extension. Frankly, it sounded virtually identical to the 8416, so I stuck with the 8416. I guess it's not all that surprising since they're both essentially of the Amperex PQ family.