RE : Hiss in The E3
The specified signal to noise ratio is greater than 90 dB. To put that in perspective my Onkyo home theater Receiver has a S/N of 100 dB and it's noise is too quiet to hear.
Twenty five years of repairing Industrial Instrumentation taught me a few things.
1. First break the amplification chain in half. Take your E3 Amplifier and power it up by plugging your headphones in but with the input cable unplugged.
2. No hiss. The noise is coming from your music source.
3. Hiss Look to your batteries. Rechargeable batteries have a limited number of charge cycles and different types require different charging methods. They may not be charging to full voltage levels. NICAD need to be flattened as they have memory. Lithium based batteries like to be charged at about 80% discharge and have no memory but only last for 300 or so discharge/charge cycles.
So replace the battery with a brand new alkaline.
Still hissing try another set of headphones.
By this stage I doubt very much that you will have any hiss and will have proved that the problem lies with the input signal and all the amplifier is doing is its job of amplifying the input signal which has noise that you were previously not aware of.
The next biggest area of problems are always to do with the mechanical components such as switches, plugs and sockets.
The least likely area of failure is electronic. When electronics fail they usually fail completely. You won't find a half working diode for example.
When I try my E3 with my Sennheiser Headphones and no input signal I can't hear a thing. But I am an old fella and my hearing starts to taper off at 10 to 12,000 Hz.
If you want to see how good your hearing and headphones are go to :
Equal loudness contours and audiometry - Test your own hearing
but be careful as you can produce sound levels which will damage your hearing.
Cheers
