Best tubes for Shanling CD300/3000 ?

I loove the Shanling sound now with my dynaudio 52se, it's soooo liquidy !!! I have the original chinese tubes. Can it actually sound better if I replace the tubes ??? Which tubes would you recommend ? I already am thrilled , I couldn't imagine getting better sound than this unless I went to a Bat or audio aero cd player. But I think the differences would be minimal.
Would upgrading the tubes make a difference?

Thanks