I just bought this B-52 all tube amp head at Guitar Center ($650 new and sounds like it should of cost at least a grand!) and I cracked it open and looked at the factory tubes and noticed Sovteks and some of them were generic and only marked China. I've looked around and seen a few threads about JJs from Eurotube.com and was wondering if it's worth exchanging them? Anyone familiar with JJs let me know if the tonal quality will actually increase that much. Also one of my tubes is making a slight chinging noise at certain tones only when the volume is maxed out and I did a little test and dont think it's harmonic as in a bad tube but this is my first all tube head and I'm not really familiar with them and was wondering if there's anything I can do to stop this sound? Such as push it in tighter or pull it out and put it back or am I turning it up too loud or do I need to replace it. By the way Im new to the forums and look forward to flaunting my godly knowledge and arguing over petty stuff 'till the wee hours of the morning with all of you.
It's probably a bad tube making the weird noise, it's happend to me.

And JJ tubes are way better than Sovteks, for sure. Bob from Eurotubes is a great guy, I recommend him(plus for me the shipping is really fast, we're in the same city).
JJ's are alot "smoother," when you crank them it isn't as grainy and the distortion is more musical. Sovteks are rather ragged and fuzzy IMO when they begin to distort.

And welcome to the forums! Great to see another member who types with a hint of intelligence!
I'm not very active here on UG currently.
I'm a retired Supermod off to the greener pastures of the real world.
Thanks for the info. I figure I'll change out the old tubes and keep them for spares. I could mix and match brands if one of the new JJs went out until I could replace it right? I gig pretty regularly and need to get acquainted with this head pretty quickly. So far I'm amazed with what I got. The tone is great but hell if JJs can improve it even more why not. And that rattle is a little unsettling but nothing too major. Even with the tube exchange I paid less than a grand for the head and cab and couldnt be happier. Im totally cheesing 24 hours a day since I got it and cant do anything without consantly planning out what Im gonna work on when I get home.