Tavish Vintage on the way - Tubes?

My Tavish Vintage Phono Preamp is on the way.
Can one of you tell me which tube has the most influence on the sound?
The input is furthest to the right and needs to be the most quiet....I understand...
What's the function of the other two? And, should they be matched? 
Any owners using any specific NOS tubes they like?
I have some nice Sylvania 6SL7WGT's that should be pretty sweet.
Thanks for your input.
Thoughts on the Vintage?  I've been using new production Tung-Sol 6SLGT it came with up until now, but have the itch to see what NOS can do.  Did you give the Sylvanias a try?  Anything else?