XDuoo TA20 tube replacement

Hi all, I recently bought a TA20, and I read in alot of chat rooms that a tube swap is needed to make these sound better. I am new to tube amps so looking for suggestion and advise on which brand or type is best.

Thanks in advance.

Purchased a pair of Raytheon 12AU7/ECC82 black plates tubes. Hope these are the ones.