I would actually try to get them tested first if possible..Even if its for peace of mind and cost a few bucks.I have even had NOS tubes that tested perfect go bad after 30 minutes of play time. I don't go out of my system area for at least a couple hours on first start up,just in case a tube wiggs out, your there to shut down as quick as possible...Thats what I do anyway.......
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?