Advice about what to do with not-needed tubes?

I was in a similar situation a while back with 12AU7 tubes. I kept the pair I liked best (Sylvania 12au7WA) and sold the rest on ebay.
Glad I kept them as I recently built a Bottlehead Crack headphone amp which uses a 12AU7 tube.

Since your system didn't benefit with tubes,you should return the tubes and go back to solid state.

You are not going to get any high offers selling them here or on ebay since they are in the white boxes and come from unknown sources. It would make a difference if you had a tube tester and could quote the test results.

If you are able to return the tubes to venders, then you'll get some money for them.

What I have done in the past, is if the white box has a vender's logo and the tube measurements on it, I will say how many hours that the tube was used (low hours) and put it up for sale. Some brands of NOS tubes will get you offers.

Thanks for the responses. Until three weeks ago, I hadn't seen a vacuum tube since I was a ham radio operator 30 years ago as a kid. So, learning from scratch. Consensus seems to be that I'm not likely to recoup my investment easily. There's a guy down the way who repairs tube gear, so I might pay him to run a tester on the tubes if I try to sell them. Some have test results provided.

@lostbears: It's a Dared SL-2000a, which I know several folks around here have owned--the reason I got it. I bought all the tubes the cool kids were using, including Brimar 5v4g, Brimar 4033s--the "blemished" white box with TubeMonger bases--plus TUngshram e80cc NIB that I haven't opened yet, as well as an RCA rectifier and Sylvania grey plate triple micas. Like everyone said a few years back, the preamp is good gear "with the right tubes." The soundstage enhancement it offered was much more noticeable on a traditional solid state amp than it was on my class D. In fact, the all-Brimar complement brought the AB amp so close to the Abletec/Tripath sound, only a bit better, that it put me on the fence about whether the investment and added system complexity was worthwhile for me. I like it, but don't really miss it, given my other equipment.

Frugality seldom wins out in my audio system, so I think we all can guess what I will end up doing. But I'll see if I'm still in the return window on the tubes that weren't ideal in my system, however. Thanks again for the feedback.

Oh, and @Timrhu: certainly swapped the tubes. I think it may have been a loose tube socket, since that one rattled just a little bit when I tapped it. Or ungrounded wire, or wire touching the transformer. Seemed unlikely to be just a ground loop, being only in once channel regardless of outlet and with nothing plugged into the inputs.

I actually had asked for a replacement, not a refund (including 2-way shipping, which was nice), but now I have the choice to repurchase, wait for a used one to go up for sale here, or to call it an educational experience and move on. The freedom to decide is nice...except when it isn't:) I'd hate to rebuy and have that one buzz to--not good for either me or the seller. Anyway, input on that issue is welcome, but I feel like I got my thread question answered by the above posts.