Ok. I by accident found a tube that sounds leaps and bounds better than any other tube I have tried in this thing. And I have tried quite a few. All the normal ones everyone is trying here.....
I was digging around in my "tube room" and found some tubes that no longer had any labels on them, and after looking the pinout up determined it was the same as a 6DJ8, but the plate structure was quite different. I said what the hell and threw one in my Aune. And holy hell, what a glorious sound. Every single thing about this tube was on another level over the Amperex 7308, Bugle Boy 6DJ8, etc etc.
Only markings on them were a capital R, and a 7....both between the pins. It also had the tale tell signs of Mullard on it....the 2 lines on the top from the point. After some research I was able to determine it is in fact a Mullard, but still not what tube it is.
It took me a few days to figure out what this tube was, but with the help of others finally nailed it. Its an ECC85/6AQ8. I have not looked up exactly how compatible it is yet, but I have been using it for 3 days now with no issues.
So if anyone else wants to give it a shot, buy a Mullard ECC85 off the 'bay. You will not be disappointed.
Here are some pics of 2 different ECC85's I have tried so far. A mid 60's Siemens and this Mullard. Both sound great, with a slight edge to the Mullard.