Which Preamp Tube is most consequential: Input or Gain

I've just gotten a pair of 1950s Tung-Sols for my Schiit Freya to replace two of the stock Russian NOS 6SN7. I will try them in both positions, but is there a typical position of more impact in terms of rolling preamp tubes in the input vs. gain positions? Thanks for any experience you'd like to share.
It all depends on the circuit they are in. Try rolling tubes in each and let your ears decide.
Thanks, in process! Was wondering theoretically as much as anything.
Place your best tubes on the right hand side forward and rear.
Thank you @ghasley . It's been hard to A/B test when I have to let the tubes cool, switch and try to remember what I heard! And @bigshutterbug per Schiit, L vs. R pairs of tubes on Freya are Input vs. Cathode follower.
No problem @peterf6 I like the Freya, its a fine preamp. I rolled in some pretty amazing 6sn7's and the personality of the Freya didn't change a whole lot. Indeed, thats a good news, bad news kind of result. Bad news is its difficult to change the characteristics of the Freya through tube rolling and the good news is, think of the money you will save not having to tube roll. YMMV, just make sure they are matched and quiet which means buy from a reputable dealer like Upscale or McShane or Brent Jesse. Peace.
I purchased one of those preamps just as Schiit Audio switched to the Freya+ and the Freya (no tube option). I started with the Tung Sol 6sn7 option instead of the Russian NOS 6sn7s. I have since switched to some G.E. 6sn7 GTB tubes from Canada. In my system they have done a better job of separating the instruments, although the Tung Sol had a bit better detail. 

I switched all four tubes though, not just two. Now I have something new to try.

Thanks @rickytickytwo . @ghasley The impact of the Tung-Sols on the right was much richer bass, on the left the bass seemed good but more in balance and everything else got nice and airy with good soundstage. So while rolling better tubes might not shift things much, stepping up from the stock 6Sn8s did. I guess I'll eventually pick up another pair and replace the remaining 2 stock tubes.Thanks for the vendor recommendations!

Place your best tubes on the right hand side forward and rear

Why would you install the new tubes in the right channel gain and cathode follower?
The new tubes go in L and R channel, either front or back.
Front would be the gain stage, unless Freya has an odd design.

Thanks, @lowrider57 , the Freya has two tubes per channel. Forward and rear are L/R channels; while the two left tubes are Input and two rights are Cathode follower. So I've been changing the two inputs or the two outputs to keep the channels the same.
The input tubes are always the place to start.
@peterf6 , ok thanks for your comments. That’s a different layout than preamps I’ve owned. Typically, tube circuit is L R in front. 
And of course, Ralph (atmasphere) is correct.

@atmasphere and @lowrider57 Thanks for that. I know zilch about preamp design despite having tube gear for 40+ years. Isn't the input side a balancing and follower for gain? Why is the input the place to start? I'm seeing it play out in my roll, but curious...
Input gain stage vs. cathode follower.
The input is where the circuit has to get it right. It doesn't matter how good things are downstream if the input fails to do its job as best it can!
@peter6- You may find the following interesting. Be certain to read the third to the last paragraph, as regards combining tube types. http://www.dehavillandhifi.com/6sn7_vt.htm

"Thanks, @lowrider57 , the Freya has two tubes per channel. Forward and rear are L/R channels; while the two left tubes are Input and two rights are Cathode follower. So I've been changing the two inputs or the two outputs to keep the channels the same."

I believe you have this backward. To be clear, if looking at the Freya from the front of the unit, the left two tubes are the cathode and the right two are the input gain stage. I don't own this pre, I'm going from memory but I believe I am correct. I remember alot of useless info not directly applicable to me, LOL!
Hi @ghasley I got my info from tech support at Schiit (quote):L/R on the Freya is actually input/cathode follower and top/bottom is l/r.

I’ll try to confirm, but so that means you were suggesting going with the input side -- which if the tech is right is where they sound best in my experiment.
@rodman99999 Thank you for sending the link! I actually found that list embedded in another forum discussion. It’s why I picked the Tung Sols Halo Getters! I read the paragraph you mentioned; so interesting. And to think I stumbled upon it just to save some cash ’-) Actually reading it more closely it's different from the similar list I read. In case you’re interested in the other info in that post: https://www.head-fi.org/threads/the-reference-6sn7-thread.117677/
Input. I’ve owned an "original" Freya for a while and can absolutely say that different tubes present a markedly different sound, with the input tubes (on the right) having the main impact on tone. After rolling between the original Russian 68HCs and various 6SN7GTBs I’ve settled on NOS GE 6SN7GTBs to satisfy my tonal requirements...that and pot smoking.
@peter6- I’d never seen that site. More comprehensive/technical, than the ancient Chimera listening comparison. Thanks! Just fyi: I had long ago settled on Tung-Sol’s Round Plate & Sylvania’s W(tall bottle/metal base), for my input pairs(monoblocks/a pair per) and bought a few of each(back when they weren’t so salty). My backups are the bottom-gettered, early Fifties, Sylvanias and Ken-Rads, mentioned in both articles. I lose just a slight bit of stage depth, with those, in comparison to the RP’s & W’s. I’m partial to a very clean/uncolored sound and found most of the other tubes(on the Chimera list), to be too warm for my tastes, after trying the top 12 mentioned. As the second article states, changing the ID of a manufacturer’s tube(ie: whether VT-231, a JAN designation or a 6SN7 number), doesn’t change it’s internals. That’s why I’ve paired different brands, to assure the avoidance of reinforcing any weaknesses. Caveat: In the past two years, some of my Tung-Sols have exhibited intermittent, internal problems, crackling like crazy, until the amp’s top plate(or the tube) is tapped(less than optimum result, from so expensive an item). Haven’t heard anything, as to whether that’s endemic(RP, w/horizontal metal supports). Have fun/happy listening!

Update (on which tube is which)
I asked Schiit to confirm the left - right pairs issue and the answer is the opposite of the previous:
FROM: Grover N (Schiit Audio)
Jul 20, 00:53 PDT


Right side is the input tubes. Front is right rear is left.