Replacement tubes for Sonic Frontiers Line 2 SE?

It is time to replace the original tubes (Siemens) that came with my SF Line 2 preamp. The Siemens tubes are hard to find (and pricey). Could some of the Sonic Frontiers preamp owners who have replaced tubes comment on alternatives to the Siemens tubes?

I've used RCA tubes in the rear most bank and was very happy. They were relatively inexpensive, and came very close to what I got from Telefunken. Also tried Amprex (not sure what flavor amprex, but I bought them new for $45) and didn't notice a difference between them and the stock Sovteks. I'd recommend sticking with the Siemens. Ya get what ya pay for.
My SF Line 1 is currently outfitted with the same NOS Sovteks Garfish references, plus a pair of NOS Amperex 7308 JAN white labels in the gain positions. After trying several others this combination is the best yet.
I used to own the exact preamp as you have now and I remember the best tubes I had on the gain positions are Siemens E188CC with A-frame (best treble extension), and the Siemens CCa A-frame(best bass and mids).
I tried variants of Siemens E188CC and CCa that does not have the A-rame structure and they don't quite sound as good as the A-frame versions. I also tried Telefunken 6922, Ampererex 7308 white label PQ, Amperex Jan 7308's white label,Mullard 6DJ8s and 6922 BVA logo, Valvo white label E88CCs and I repeat none comes even close to the two tubes I described above. Of course this are all just my opinion on how they sound on my system back then.
Hi All,

I have an SF Line 2 on the way.  I will be using it with a ModWright Oppo and primarily listen to digital media. I also recently purchased a Conrad-Johnson MF2275, so there's that....

I am looking for a 'dark liquid' sound.  Not 'warm' or 'bloomy', certainly no glare or blare. A hint 'woody' would be alright. Tightly radiant and/or illuminating would be good.

So what tubes can you all recommend?  

Thanks so much for for all of your shared experience.