On this newer production run, you may expect the majority of the output to be at 2.3k, with practically no bass or upper treble. This can be fixed with a headphone amplifier; however, this description doesn't match the classic Pro-4AA. What you have here is a newly redecorated Pro4AAA, and that's not the same thing. Therefore, what you receive probably won't match what you expect.The classic Pro4AA is gone. Only its appearance remains.This new item can work for voice communications, speech therapy, language learning, and many other applications where a voice-only response is appropriate. They're also useful as a movie prop.I had mistakenly purchased these for music, not realizing that they had been changed.