These came along with other tubes with an amp I bought, without any information about age or condition. They sound wonderful, with no noise or other audible issues but I have three other sets of 6L6’s and don’t need these. On a couple of the tubes the RCA 6L6 logo is intact and it’s partially there on the other two. The ‘RCA’ printing on the base of two of the tubes has ‘CU’ printed in small letters underneath, the other two have ‘CZ’ and ‘DE’. Two are in original boxes and two in white boxes. The flaps on the original boxes have some tears but still work. I have no way to test them other than listening and can’t tell anything about what it takes to bias them since my amp is self-biasing. Make an offer Free shipping to the U.S.
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