I like the Amperex Orange globes for the Vali 2. More natural than the stock tube better bass presence with a richer tone. Mids are nice, warm with good body, vocals have emotion and feel but a ever so slight grit in the treble which I believe is inherent with the Vali2 but it's not a big deal. Make sure it's the ones with globe on the tube if you are interested because there is some amperex with orange writing and they suck.
Buggle boys are good, good treble air, extension and both ends, fairly neutral with a energetic turn. You could also try the Mullards in that family that have a more HD650 character, rolled off at extremes but super focused in the mids, best vocals I've heard come from Mullard tubes.
