[FullRangeMan]

Have just see that the reliable GSTubes Shop(Andrey and his wife Natacha) have in stock again the rare 1578(6SN7) metal Base and the rarest great sound Perforated Anode at just $38usd /each made by the traditional Melz Moscow factory.
https://www.gstube.com/catalog/?key=6h8c&submit=Find

[JakeJ]

Thanks, FRM!  Just ordered 4 and am awaiting total with shipping.

Don't know if I recounted my experience with buying 24 6H23n tubes for under $5 a pop IIRC (about $20 each from US vendors).  Got the box and tested them immediately.  Production dates were all over the map but the early 70's ones are awesome.  Got two nice strong quads, a few lesser testing pairs that are close and two outright duds.  All in all quite happy with the results.  Looking forward to hearing the 1578 Melz's.