To answer your question, tube rolling can affect bass to a minor degree. FME, bass is mostly affected by the room and speaker location. Smaller bass adjustments can be had by equipment, amps, preamps etc. Smaller yet bass adjustments can be had by cables and power cords. Tube rolling comes in next, and probably last for bass adjustments. You can find some tubes that may have some minor affect on bass. In my tube rolling experiences, I've noticed most differences in tubes lie in the midrange, high's, soundstaging, and aspects like that. Bass to a much lesser degree.
Cheers,
John
Cheers,
John