I finally got a chance to install my new 6550 Tung Sols this morning. This has got to be the sexiest looking tube ever made!
Of course it takes a good 50 to 100 hours for any of the tubes to sound really good but these sounded better than most tubes do when you first install them. I was listening to "50 Ways to Leave your Lover" by Paul Simon. I could pick out the kick drum right in front of me, a lower kick drum about a foot to the left, the snares slightly to the right and a little further to the right was the hi-hat. This recording and tube has the soundstage correct! I could even hear things at the correct height. For example the kick drums were at the floor, hi-hat at the top and snares in the middle. Voice was slightly right of center on this song and slightly higher than the hi-hat. The main thing I believe will happen after burn in is that the voice which now sounds slightly edgy will smooth out. So far so good!
BTW, I'm using Electro-Harmonix 12ax7's and 12at7's. So far they have become my favorite over all the NOS tubes I've tried. Cheaper too.