Having owned the board before I can make the comment that different tubes do sound different in the driver board. The JJ's seem to have more high end in my opinion. Some of the NOS tubes have a nice laid back sound. Buy some tubes and experiment a little.
Some circuit designs you can tell a difference rolling the input/VA tube and some the phase splitter tube and some you can hear difference rolling both tubes.
My current favorite designs use either a 5693 and 5691 per channel or a quad of 6SL7/5691's. I can hear difference rolling either the 6SJ7/5693 or the 6SL7/5691 on one board or rolling both sets on the other board. I feel that with a good stiff power supply the differences come to play. Also speakers play an important part in your system. I can hear more with my Klipsch Cornwall clones than I can with my Altec model 9's.