12BH7A-STR - TAD Tubes, Premium Selected

I started tube rolling from 12AU7 tubes to 12BH7 tubes for my headphone amp. Make sure your device supports it before rolling. I read on forums people say TAD has bad QC and it is rebranded Chinese tubes. I decided to give it a try. If it sounds good than it is good.~stock 12AU7: muddy bass and everything else is rolled off~Genalex Gold Lion 12AU7: very bright and 5hz spike. Terrible sound and very expensive.~Electro Harmonix 12AU7: very smooth sound but it is a little congested. Mid focused, bass and treble slight roll off.~Electro Harmonix 12BH7: sound almost like Genalex Gold Lion 12AU7 but separation is worse. Very harsh around 3-5khz. Electro Harmonix 12AU7 sounds better and I was disappointed.~TAD 12BH7: bass and mid focused, 2khz forwardness, and a bit of treble roll off. Better separation and sound stage than Electro Harmonix 12AU7. Vocals are the stars for these tubes: they are forward and warm sounding.I was surprised of TAD's sound quality. What I noticed was 12BH7 tubes produces more heat compared to 12AU7. 12BH7 has slightly louder volume than 12AU7. Your mileage may vary for tubes and your gears. I recommend to give TAD a try. I will give an update if TAD 12BH7 stop working.