I have the 34 DAC so it is a little different using four tubes. I am using Amperex 7316 PQs and Amperex 6922 PQ Goldpins. I have used Bugle Boys, D-Getters and Orange Labels but the 6922s really added more bass, cleaner/clearer detailed sound, different mid-range not as dark sounding and more dynamic then the D-getters and Orange labels. Each tube changed the sound slightly but the 6922s were more of a change.
Hope this is helpful.
Hope this is helpful.