LOL, not the king but I enjoy trying different things so I just went nuts and tried literally EVERYTHING everyone on this site recommended. These guys rule. There is only one tube. First I got the AD50VT but it had a ton of problems so I sent it back but I'm sure the tube swap will affect the tone of your amp as well. I took Jumpmarine's advice and removed the rubber ring around the tube then wrapped some packing tape around it and wiggled it back and forth while gently pulling. Came out like it was greased.
As far as what Gearjoneser said, my amp may have just had a really bad tube because the difference from the STOCK tube was night and day. I didn't even keep it as a backup. I threw it away. However, the differences between the three "good" tubes were just a matter of preference. All three sounded great. The third one I used by the way was a NOS Mullard 12AT7.