Used tubes question


I bought a used quad of xf2's. They were cheap, 150.00 bucks, so I figured I'd give this older-mullard-tube-thing one reads about so much a listen. Now I worry about putting them in my intergrated. I have a Leben CS-600 and fear it going up in flames. The seller said they were closely matched and tested on his such and such tester. He had plenty of positive feedback. Should I just pop 'em in and see what happens? What is the worst that can happen?
128x128oldsalt
but buy stock factory brand new tubes

IMO ,I totally disagree..Ive bought tons of used tubes on ebay with no issues.Mullards,Seimens etc etc,Seems rather silly to spend twice the money from a tube broker or buy inferior "new" tubes when the real deal stuff is available on the bay.Get a tube tester.They are everywhere,cheap enough and its kindof fun to test them..
Given the seller's good feedback, I suspect you'll be fine. I too have bought lots of old tubes with no real issues.

Old signal tubes rule.
Agree with Steidlguitars.

Buying old used tubes is a good way to go. I've been particularly lucky along these lines.

Normally, these older tubes have held up very well over time, a tribute to build quality which is not replicated today. If you can give up the snob factor of NOS, there are some real gems to be found at comfortable pricing.
Thanks everyone.
Any suggestions on what to look for in a tube tester? And, will testing tubes keep me from damaging my amp? What should I be on the look out, or, ear out for, when I turn the amp on that might signify a problem? Distortion? Weird tube colors? 10 foot flames?
Thanks again.
They sound fan-f*ing-tastic. Wow. I'm going to save up for a NOS pair or two. Wow, wow, wow....