First of all I want to say thank you to those encouraging me to get Amperex instead of Bugle Boy that offered locally. I get a better deal, threesomes tube but just a tad higher than the local BB. And thank you for providing me the link. I'd been spoon feed or tube feed by this thread member.
Amperex 6DJ8/E88CC is here. Just spend 1 hour testing them all but with short time, noticeable upgrade from EH6922 would be:
1) No more ear piercing sound.
2) Music becoming less thin, add a little body.
3) Better bass impact.
4) Larger soundstage.
5) Suitable for metalhead music. (I'm a metalhead but at the same time listen to other genre.)
6) Not just metalhead, improve music in EDM and R&B too. In other word, universal improvement.
However, the bass less rumbling inside my ear but I'm okay with that since I'm not a bass head. Plus, no more ear piercing bright. IMO, it's still bright but it's more like polite bright, better than Beyer bright. I tested EH6922 with Xduoo TA-01 amp before and it's warmer than T1 with 6DJ8 and stock tube along. But again, HD600 is a neutral headphone and some considered as bright.
Now I waiting for Crack. Let's see how Aune T1 pair with Crack will do. My current aim is looking for mid entry tube DAC, I love tube!
BTW, I bought my tube from ebay, took me 3 weeks. Well, about 5 weeks. 3 weeks to arrive at my country, 2 weeks stuck at post office.
I can't here any obvious different between these 3 tubes.
It seems you managed to get 1 single leg GAC coded also! This should be best out of them.