After having gone through more than 16 6sn7 Nos tubes last 6 months.
My recommendation is
If you like full bass and wide and deep soundstage , then you shall try Melz 1578.
https://www.ebay.com/itm/Matched-pair-Extremely-rare-1578-6N8S-audiophile-6H8S-6SN7-Metal-base/273874731266?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
This dealer replaced a noisy tube quick and easy.
Melz 1578 had been staying in Line Magnetic 508 amp for the last 3 months.
Sylvania vt 231, Kenrad vt231, RCA vt 231 are recommended if they are priced under 160$ pair with good measurement.
My recommendation is
If you like full bass and wide and deep soundstage , then you shall try Melz 1578.
https://www.ebay.com/itm/Matched-pair-Extremely-rare-1578-6N8S-audiophile-6H8S-6SN7-Metal-base/273874731266?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
This dealer replaced a noisy tube quick and easy.
Melz 1578 had been staying in Line Magnetic 508 amp for the last 3 months.
Sylvania vt 231, Kenrad vt231, RCA vt 231 are recommended if they are priced under 160$ pair with good measurement.