I currently test a Stax 9000 that the distributor send to me for that purpose. I like the sound, but I hesitate to buy the Stax because there is a big differene in volume on the left and the right side. I use a Mal Valve head amp III MK 4. I cannot compensate the difference in loudness by adusting the balance. I do not experience the issue with my Grad 3000 e. I should add that the voices also tend to be more on the right side and not in the center with the Stax. The same female/male voices on the Grado seem to be right in the center. I have rotated the headphones from left to right an now it sounds a lot louder on my left ear.
Are you sure the cable is fully and properly seated for both cups? Fully and properly seated at the amp end?
I ask because I have had this exact experience with other headphones and it turned out I just needed to take the kid gloves off a little when plugging them in.
Thanks, yes properly seated at both ends! The left side becomes weaker and weaker. I think that I have an issue with the headphone and not with the amp.
Borrow a proper STAX Energiser and test with that before ruling the headphone as the problem.
You wont have the same issue with the Grad as its not an E-Stat so is using a totally different amp circut to the energiser section which is pure voltage and that might be the issue.