I liked Amperex Bugle Boys (made in Holland)in my 128. Warm natural bass with good extended highs. I've been intending to run some Seimans 7308's but I haven't yet. I would expect from this combo dynamics and bass with mid-range and high end clarity, but at the expense of some warmth. Just a WAG though!
However, I think your choice may be dictated by your associated components more than anything else. I'm using mine with Primaluna stuff and the 6922EH supplied by the manufacturer seem to fit better than the other tubes I've tried (EI's/Teslas NOS/JJ Teslas/6H23EB's/Sovteks and Amperex).
However, I think your choice may be dictated by your associated components more than anything else. I'm using mine with Primaluna stuff and the 6922EH supplied by the manufacturer seem to fit better than the other tubes I've tried (EI's/Teslas NOS/JJ Teslas/6H23EB's/Sovteks and Amperex).