It depends who you order the TU-8500 from what your tube options will be. I'd say build it and break it in with whatever tubes ship with it. Don't go crazy hunting down pricey NOS tubes right away.
Tube preferences don't travel well from one amp to another. There are just too many variables. A tube that sounds good in say amp A, with whatever your terms of reference are, might not be your favourite in amp B.
I've heard the TU-8500 with the previously mentioned 5965A tubes. It sounded pretty good and they're only about $5 each. A couple of ancient used and abused Telefunken ECC82s had that magic midrange/softish treble thing going on if that's what floats your boat. Me, not so much. I prefer a more neutral sound with good pace and drive.
Balanced tubes in this instance likely means the two sections inside a dual triode closely match.
Do you have much DIY audio experience? If it's only a line stage you need (the TU-8500 and a SS phono section) maybe a line stage-only project might be better for you. As always it comes down to budget too.
S.
I'll order the elekit here :
https://www.jukebox-revival.eu/elekit-tu-8500-voorversterker-bouwpakket.html
Stock tubes are 2 x 12AU7 (ECC82 from JJ). No extra options except 200€ extra for a pre-builed.
I'll wait and see how the stock tubes perform and then I'll have my first reference point to compare.
I have zero experience in DIY audio but I am verry handy, have been an electrician for 12 years in the past, and have done some soldering in my life.
My older brother who works at Siemens has a high degree in electronics and he will teach me (again) how to solder and what to watch when building.
I really need a new preamp as the best/most expensive part of my system are my speakers (and I want to let them sing!) and when asking on many cabasse forums, everyone points to the Rotel preamp as being my weakest link and cause "harshness" in my highs.
The topping D90SE being verry transparant emphasises that harshness more/extra.
When I use the preamp built in the Topping D90SE I have a slightly less harshness but overall sound image/quality drops, less body.
I'vs been looking at Schiit saga+, ifi Itube2. The freya would be too expensive. Budget 500-650.
I think the elekit 8500 will outperform those, so I decided to go for the Elekit-8500.
In my search for tubes the last days I did come across some good tubes to put on my list eg the telefunken ecc82 60's smooth plate (as you mentioned) or a siemens ecc82 60's. Valvo 12au7/ecc82 long plate o-getter is also on my watchlist.
Ebay germany has everything.
Again, thank you for the assistance.
