[Berndt]

Hi guys, use the 6sl7 in my phono stage and have been using a rather expenive set of blackburn/mullard ECC35's.
The 6h9c's have a more esoteric variant that I have tried, the 1579.
The plain jane 6H9C is available off of ebay for less than 5$ ea and only give up a touch of refinement to the mullards, having great sound stage and dynamics. We'll see if I can get some longevity from them, alas my 1579's got noisy after a few months of use.
Justa heads up.
Regards, Bill

this is what they look like...
http://cgi.ebay.com/6N9S-6H9C-6SL7-Lot-10-Tubes-NOS-NIB-/250627727168

[Berndt]

belay my last, I blew it in regards to this suggestion.
I should have waited a few weeks to see how things progressed.
Tubes got microphonic quick, sound great out of the box then microphonic city 24 hrs later.
Please forgive my misplaced enthusiasm.

[grubyhalo]

Thanks for taking the time and sharing your experience.