replacement tubes for decco

i just recently built a brand new system:
lossless-->decco-->anticables-->totem rainmakers

after about 80hrs of listening, both the decco and the rainmakers are opening up nicely and it gets better everyday...overall im extremely happy with my setup.

im now wondering if switching out the 6dj8/6922 in the decco would make it sound even better. any suggestions would be greatly appreciated, especially from someone with experience with the amp.
considering the decco uses a tube pre-amp and headphone section it could make quite a difference, if used with good old stock E88cc.
dremer, do you have any specific recommendations?
This last month I have been rolling different brands of the 6922 family of tubes. The NOS Amperex and Siemens always seem to be at or near the top of the list and this was true for my system.