Tubes for Counterpoint 3

I am making my first tube purchase for the Counterpoint 3 mostly for the phono section. i will be using the phono stage for now through a B&K PT3 mk2. The unit comes with two 6dj8 tubes in the phono stage. Would I gain anything by replacing the tubes in the phono section with higher quality tubes as an inexpensive improvement. If so, what tubes are recommended.....

Thanks for the advice.....

Eagleman