I had been tube rolling with Line Magnetic 508 and Schitt Freya using various Nos 6sn7n and 6sl7.
So far my favorite with LM 508 is Rca vt231 and RCA 5691.
Out of curiosity, I had also pulled the trigger for Tungsol bgrp( holy grail ? claimed by some folk) which I expect to get next week.
Schitt Freya is also nice preamp in my headphone setup.
Sylvania vt231 in gain stage and RCA gray bottle in buffer stage give ideal combination of details speed and wide and deep soundstage but without hot edges.
Freya in the chain make sound out of 009s, sr1a and hd800s more refined and musical.