Here are some of the best rectifiers for audio. 1 pair with back base and another pair with brown base.
The brown base are labelled Zearix but are in fact Cossor made. Used but measured as new. Only 10 hours of use. Both are matched. Does not come with box.
The black base are Cossor labelled CV378. Never used and measured as new. It comes with box and those ice cream cone protectors. One of the black base has a rattle in the base. Will not affect operation.
Brown base are 225.00 each. OBO
Black base are 280.00 each. OBO
If interested I can provide pictures of tubes been tested on my Hickok 752 or Jackson 658A.
Shipping and paypal fee not included in price.