Can tube rolling change bass?

I agree with Cyclonicman that deep bass is not mainly provided by tubes, though they can be considered a tweak. As such, I think he would obviously agree that because some tubes supply more warmth and fullness, one might perceive or experience more of an apparent enhancement in mid and certainly upper bass/lower midrange performance. I have certainly found this to be true using Mullard 12au7s and Brimar 12ax7s simultaneously in my Air Tight ATM-3 monoblock amps. Of course, utilizing such a combination as this may, for some ears, also manifest an unacceptable degree of masked detail from the midrange on down. As always it comes down to a matter of personal taste and satisfaction.

Obviously, I should have also noted, perhaps more importantly, that one may or may not like the sound "coloration" per se provided by the Mullard/Brimar combo. I place quotes around the word coloration because some consider it a departure from the reality of so-called unamplified music. In most instances I would reject such a claim, since widely varying colorations are found from concert halls to open air venues(with effects produced by wind, humidity and air temperature)as well as being associated with equipment that involves the recording and reproduction of sound in the studio, audio salon and home. Further, this may raise questions regarding the validity and/or meaning of the word neutrality.