Originally Posted by Luisfc1972
i get a hissing sound when usingt computer headphone jack to lepai ta2020a+ headphone jack, but, i do not get a hissing sound when i connect to the ipod. this happens at low volume. im using 6 ohm pioneer bs21 bookshelves.
Any ideas why the hissing sound only from computer?
If memory serves, a Lepai TA2020 is a switchmode power amplifier based on Tripath chips. I've worked with TA2020 amps in the past and had them on my test bench. Its output terminals are loaded with ultrasonic tones from the switchmode amplifier.
The hiss is probably intermodulation products due to high frequency nonlinear distortion in the laptop's audio interface.
Much has been written on this forum about the possibility of things like this happening, so thanks for a practical example of it.
Hopefully, you will complain to the computer's manufacturer and if possible return a number of samples, driving up their waranty costs to the point where they will be more careful about what they try to sell. A simple low pass filter composed of a few pennies or simply more care in the design of the audio interface chip would solve this problem.
If you check out the Device Manager, what audio interface is in this computer? I'm hoping that Realtek (the largest manufacturer of this kind of chip) isn't falling into this kind of hole.