best tube for unico cd & 80w amp.

i just got this unison pair, should i upgrade both cd and amp. with the same tubes or just the amp. i am new to tubes, the combo sounds great already, but i have read a tube change can make a big difference
My advice would be to make sure that you've listened to the combination long enough to fully know how they sound. Then, change the tubes in only one component at a time to see if you like the results. Personally, I like Brimar 13D5's in my Unico amp.