They don't list output impedance. It may not drive SS amp optimally. The thing about ANK is output transformers and low impedance. They have quite a bit of experience with top, proper AN UK designs costing obscene amount of money. 6SN7 is likely " all you need tube " and that's why all the fashions fade away and 6SN7 remains. Its simple and effective. I personally hate caviar ( maybe I never lucked out on a good one ) and champagne leaves me cold as well . That's about it if it comes to so called hi life experience I have 🙂
Re output impedance, I guess you could always ask the Canadian importer https://www.diyaudio.com/community/threads/elekit-tu-8550-pre-amplifier.385135/?