Just picked up a Little Dot, and some matched GE 5654W's for it, and kinda like them, but found that, while the stock 6JI's are too forward in treble and upper mids (among other faults), I did find the 5654's a bit too laid back in comparison. I found the amp to be a bit veiled, perhaps even slightly congested, compared to my SMSL M6, but still think it sounds a bit nicer--At least for casual listening.
I've got an AD832ANZ on the way, to replace the op-amp; I've heard the stock is in part the cause of congested sound. I'm hoping this works, and will improve the listening experience. I'm also considering a pair of Voskhod 6ZH1P-EV's, as I've heard they are quite detailed, and I'm a detail-freak.
I'd like to: remove the veil/congestion, and find a slightly more aggressive and analytical op-amp/tube combo, for critical listening+rock purposes.
UPDATE: Got a pair of 1976 gold-grid Voskhod 6ZH1P-EVs for $15. Takes a bit longer than amazon prime...but should be worth the wait. I've heard they are very detailed and rather forward.