Wilson - I'm a JoLida fan. I used Ei Elite 12AX7s and NOS Mullard 12AT7s with Winged C KT88s in mine. Never tried 5751s. You might want to check out Tube Monger if you haven't already. They have interesting stock and possibly some suggestions for you.
Jolida jd-502p
Anyone using 5751 tube to replace 12ax7's in a Jolida. I have read that it may not work well with some circuit designs. Also curious about what other Jolida users are using?