Where to put 4 tubes on a 6 tube preamp?

I just picked up 4 really nice Amperex 6922 tubes for my 6 tube Sonic Frontiers line 1. I was wondering were to put them (and use the stock Sovtek for the other 2 inputs)?
Is this a good idea? or should I just pick-up two more Amperex tubes. I've heard it mentioned that you really only need two good tubes and that the other inputs are for bias control, but can't find any real info on this.
It depends on the circuit design where the most influential place to put them is. Chris Johnson (founder and former president of Sonic Frontiers) now runs The Parts Connexion, and has always been very helpful with all things SFI-related . . . you might give him an email.
If you get the service manual from mad Manuel's manuals on ebay it should tell you where it matters.
BTW I understand that only a few tubes can be used in a SF. Amongst them are the Sovteks are you sure the Amperex won't become expensive toast.
I would ask Jim McShane over on the tube asylum or just search the archives.
Doing a search on the A'goN forums for "Sonic Frontiers Line 1" turned up the following threads:




Pretty much everything you might want to know there including what positions and tubes are best.

BTW, I owned a SF Line 1 for a few years and used a variety of NOS tubes in it without any problems.