Maybe the lack of bass(dynamic headroom?) is not because of the tubes but the amp/headphones combination ur using..maybe ur amp is not powerfull enough to drive ur headphones to their limits?? Maybe a stronger/better amp can remedy ur problem? What headhones u use and what amp u use them with?
Woo audio WA2 and beyer T1. I don,t have a problem with this setup, i like it, i just wanted to know what were the darkest tubes. I am ordering 7236 soon and then i wanna get really bottom heavy ones jsut to a the variety. The 5998's are great.