Linlai E 6sn7 tubes

Any opinions on the importance of Grant Fidelity's "top 10% Ultra Low Noise" rated tube designation as opposed to buying directly from China? I need only one tube for my Dehavilland preamp, went to the Linlai website and they were only selling them in pairs. In a Senior Moment I forgot about Grant Fidelity as a possible source and ordered the single tube from a Chinese distributor on Ebay who has an excellent rating. By the time I remembered Grant Fidelity as a possible source (and they do sell them as singles) it was too late to cancel. So, am I forever doomed to neurotically suffer from those incessant ruminations that my tube will not be performing up to its potential, or is this tube grading mostly a marketing ploy?

@lowrider57 The Linlai website does not grade their tubes, one could assume that their buyers should consider their purchase as having passed a Linlai quality control standard. That leaves me with my original concern that the tube I will be receiving may be of a lower quality even if it is a genuine Linlai tube, perhaps a Linlai "reject"? At this point I just have to wait until I receive it and listen to it, which, other than its reliability, will be the ultimate test regardless.

@lowrider57 The vendor does not list them as a Grant Fidelity tube. The pictures shown are not detailed enough to show any markings on the glass. It does show a "plaque" on which is engraved "Linlai Tube E-6sn7 - 01512". When I receive the tube I will look for "PVT" stamped on the glass. I was under the impression that GF's low noise designation was just a tighter spec and not a different structure tube, but I could be mistaken.

Thanks for your reply.

Anyone have any experience with the Linlai Global KT-88-D tubes??