12AX7 tubes for headphone amp?

Does anyone have any recommendations for 12AX7 tubes to try in my Vincent headphone amp that uses a single tube? The one that came with the unit is fine, but I'd like to experiment with other brands of 12AX7. I've read quite a lot from various webpages on tube rolling and the differences in 12AX7, but your opinions would be very helpful in selecting a couple or three to try.

Thanks,
Bob