Primaluna Dialogue 2

I need some help with the small tubes. There is a pair of 12ax7 in the middle, and a pair of 12au7 outside of them. What does each tube do? If I were to use a separate preamp and access the amp section only, which small tube would be in play? Thanks!
Anyone out there?
Well, this is an integrated, means preamp + power amp in one, and I am not sure how do you want to use it as power amp only??? The 4 valves you mentioned are pre-amp section valves.
Thank you. Do you know for a fact that all 4 small tubes are used in line section?

The Dialogue 2 has HT bypass inputs. This means that its amp section can be used separately by running an outboard preamp into. I'm guessing that one pair of small tubes is for the line section (either gain or buffer), and one pair is for amp drivers.

This is why I ask the question. If I use the amp section only, the line stage is not in play and I can use any ol crap tubes in there, and I only need to concern myself with rolling tubes in the amp section.
Well, I didnt know that, hmm, sounds logical, but may I suggest you to send an e-mail to a manufacture, cos they seems to have a great customer service, especially when you have such specifiek tech question.
Just saw this - Maxmad is correct, all four smaller tubes you are asking about are the line stage, and the four larger ones are the power tubes. My understanding is that when you use the HT bypass, it bypasses the linestage, as the HT receiver is functioning as a preamp, so the smaller tubes would not be in use in that situation at all, but this could be incorrect. I have not yet used mine as part of a home theater system and don't plan to for some time yet, I have only used it for two-channel listening. You should contact Kevin Deal, I think his name is, at Upscale Audio, who is the US distributor of PrimaLuna. Please let me know if what I said here is incorrect!