I am with you that the HA-SF is a great Amp with stock tube. After our Discussion concerning the JJ Gold Pins im pm my Dealer of choice. In case this is true i would change all my ECC-99JJ. First , he recommendend to try a NOS Driver Tube. (Thanks to
pgkrish!). I bought a NOS Telefunken ECC82 from Germany. I was surprised to found out it didt not change the Sound to the better. So back to my Dealer, he offered me to check my 4 ECC-99JJ. 2 Days later he contactet me an told me the Set is not matchet or has be damged. I asked him if i should order 4 matchet ECC-99 Golpins. The Answer was short and clear. The Filament of the Goldpins ist identical, and as long the sockets has no Goldcontacts it makes no difference. He could easyli Sold me the costlier Goldpins, instead he check my Stock Tubes for free (with diagram). I got 4 matched ECC-99 JJ and he send me a alternative to the Telefunken - A NOS Sylvania
6189W / 12AU7 PH - JAN/NOS to compare.
After (80 Hours) implementing the matched ECC-99 the hiss from the right channel was gone(even when i was minimal). The same with the weird sounds from the left Channel. An indeed the Sylvany NOS Driver was the most important Update. I am not saying the Stock Tubes i received from Auris where inferior. Maybe something happanend while shipping, maybe i drank to much an damaged them
![Beer Chug :beerchug: :beerchug:](https://cdn.head-fi.org/e/headfi/beerchug.gif)
. After this experience i have to Ask:
Are you sure you got the best assembly ? Have you testet if your ECC-99 are matched ? I am quite shure this should be the first Priority !