I really want to hear my Beyerdynamic DT-990 with this amplifier but unfortunately the price is too high for me. I have experience with electronics and I could do it myself, but the input and output transformers are particularly critical components and largely determine the sound. I will ask those of you who own this amplifier to share more information about the transformers.
For example, if the input transformer is a standard one that is manufactured by another company and can be purchased?
The output transformer I guess is made by EAR? But anyway, if anyone has this capability, he could measure some key parameters of the original transformer, such as inductance, active resistance, winding ratio, dimensions and so on.
The idea is to have as much information as possible to make the transformer with parameters as close as possible to the original one.
I know very well that this in a very difficult task and the amplifier will sound different from the original, but this is still better than nothing. I wish I could give $ 5,000 for a real EAR HP-4, but at least for now that's impossible for me. I will be glad if someone gives more information about this amplifier.