Why does noise appear in the amplifier when connected to a computer?

Question

Batteries

I assembled a homemade headphone amplifier, it works in class A. The PCB layout is normal, it is assembled cleanly, the power supply is well filtered, all signal wires are shielded.
And the problem is this - if you connect the amplifier to the computer, then there is noise (hiss, no hum), Asus Xonar DX sound card. It can hardly make noise, because I connected another amplifier - everything is clean. If you connect to the phone, then everything is fine, only noise from the phone is heard.
Why does this noise appear and how to get rid of it?

Answer 1

There may be interference from USB, video card, Bluetooth mouse. The wire is unshielded and the magnetic field from other devices may affect the audio signal. A simple solution: identify the component that gives the pickup and turn it off. Expensive - buy an external DAC or sound card.

Answer 2

The sound card does not pull, there was such a problem once.

Answer 3

Has the problem been solved?) A typical ground loop via USB, the easiest way is to simply glue or unsolder the ground at the amp power supply.