In this instance, I would like to hook an output of my audio interface (1/4in output on a focusrite 18i20) to the mic input on my PC (just standard 3.5mm input on the motherboard).

I see a bunch of answers on this site, but I do not know if the input levels on a PC are different than other equipment.

2 Answers 2


You will need to attenuate the output (of the line level output) by at least 30 dB, or you will over-drive the input (of the mic level on PC).


"output of audio interface" implies that there is a high-quality digital audio stream available. A mic level input on the PC has a really lacklustre sound quality and ends up with a digital audio stream.

The only conceivable purpose I can think of is measuring just how bad the sound quality is.

If that is your purpose: the mic level input is comparatively high level and low impedance. It carries DC: it depends on the output circuitry of the audio interface whether it minds that. When in doubt, add a blocking capacitor, something like 4.7µF should already do (assuming 2.2kohm input impedance, a typical value, that results in a highpass with 15Hz cutoff). Other than that, your output level control should be enough to get the signal strength under control. Normal output level would be about +4dBu while you probably want something like 40dB less.

If that isn't your purpose: think again. The mic input on a PC is of mediocre quality.

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