Great comments and advice from @tomcy6 . I'm a firm believer that each type of tube and each manufacturer has it's own sonic signature. Typically, you don't need to swap all the tubes from stock to vintage, aka NOS tubes (New Old Stock). There are specific tube locations which have greater influence on the amp's sonics. Most of us start with the small signal tubes, but you need to know the function of each tube in its location. Sometimes the user manual will state the function of each tube stage; eg, preamp, amp gain stage, or driver stage. Contacting the manufacturer or dealer is a better way to go. I won't give any advice on tube selection since I don't know your amp and since you're still getting to know it.
I'll cite one example of a tube which provides an increased emphasis on the midrange and has plenty of "air" in the highs; it's manufactured by Amperex. Some tubes will be more linear, some will add detail to music, some will add warmth, etc.
Here's a primer on tube sonics of different manufacturers and each tube type; You can click on 12AX7, 12AU7, 6SN7.
http://www.audiotubes.com/12ax7.htm
A member who is familiar with your amp very possibly will chime in.
I'll cite one example of a tube which provides an increased emphasis on the midrange and has plenty of "air" in the highs; it's manufactured by Amperex. Some tubes will be more linear, some will add detail to music, some will add warmth, etc.
Here's a primer on tube sonics of different manufacturers and each tube type; You can click on 12AX7, 12AU7, 6SN7.
http://www.audiotubes.com/12ax7.htm
A member who is familiar with your amp very possibly will chime in.