Signal tube versus power tube, sound impact?

. . . what a representative from the sales department at Cary Direct once told me (the Cary people will actually talk to you on the phone if you want to buy something) when I called to inquire about the Amperex Bugle Boy 6DJ8s that Cary Direct was listing:  "Tube rolling will make you neurotic."

That is a direct quote. 

And yes, I did buy a pair of those 6DJ8s for the front of my Cary V12.  I don't recall being overly impressed with any changes to SQ I might have heard, and presently those Bugle Boys are back in the "tube drawer" of a file cabinet I have and I have a pair of Gold Lion 6922s in those sockets.

. . . I also meant to say that although I personally never heard huge sonic differences when I was going back & forth with different HEALTHY output tubes in my first two 6550 based amps (I have never rolled tubes in my present EL34 based amp as long as it was running with HEALTHY tubes), if I had an output tube or tubeS that were getting sick or were getting tired, replacing output tubes was then  like listening to a new amp.

My experience is like @ghasley.  Small tubes in pre stages made way more noticeable change than output.  Using NOS recommendations from both maker (Raven) and Brent Jesse I chose military and or scientific grade pre tubes.  Stage expanded and bass tighter at every position tried. I ordered unit with one step up in 2 of the 3 positions too.  Most run cheaper than output tubes.  I then tried better/desirable/ recommended output tubes havibg been so happy but its much more subtle a change.  YMMV.  I set a budget and said I'd stop if if I didn't hear any improvement with each position.   But it did improve.  Done now.  2 years "sober".  Not neurotic. Besides, I now have perfectly decent spares.   

@akgwhiz  , it is always good to have spares.

Not knowing what your tubes are definitively (did you actually confirm they’re JJ - you seemed uncertain…), nor the amp, speakers etc., this is not a realistic query for anyone to field.

More supporting input due from ya. 😉