I just got a fun little Blackheart 5 watt head. Great little amp and loud! EVERYONE has told me to replace the stock Chinese tubes, which I did post-haste. The amp had no hiss or buzz with the stock tubes, and now has a horrible white noise hiss. I put in a very expensive preamp 12ax7, private selection BS or some such thing from one of those tube store or depots off the net. Ya, I fell for the hype. It was like 65.00 or some such ridiculous price and supposedly "tested". Made in Canada? Well, its a pos in my opinion. I also put in a JJ el84 power tube. The amp sounds better, but only by a thin margin and it hisses worse than a snarling woman on pms. What to do? Love this little amp. Any suggestions for a good preamp tube from normal tube supplies. I'm not looking for NOS or any other BS.