Google translate:

Quote:
Last Sunday came the M-Audio AIR 192/14 card, the Ammoon condenser microphone without power supply (thankfully the card is equipped with Phantom power supplies) and then the Shure SRH 440 headphones.
I have some questions to ask you if you want,
1) After installing the card driver, and after connecting the Ovation guitar I turned on the card, I immediately heard a rather annoying hum in the headphones and by decreasing the gain of input 5 (electric guitar) the hum decreased. Even the hum disappeared if I touched the board and the guitar strings at the same time. Could you tell me if the problem is with the guitar cable or something else?
2) In the audio control panel of the PC I cannot use more than one device for both playback and recording, so I can use two electric guitars but not a guitar and a microphone at the same time. In the audio control panel I tried for Recording the selection of the M-AUDIO AIR 192 14 Multichannel device but the result is the same. Do you have any suggestions?
I have the same interface you do.

There are 8 channels — you can plug into any of them on the M-Audio AIR 192/14. Normally, 5/6 are for guitars and keyboards that do not have line level outs. Is it any different when you plug into 1–4?

The real problem is grounding or shielding — rather the lack of it. Unless you have a faulty cable, the issue is your guitar.

Before I write 10 long paragraphs about all the possibilities and solutions, what kind of guitar do you have and what kind of pickup(s)?

BIAB 2024 Audiophile Mac
24Core/60CoreGPU M2 MacStudioUltra/8TB/192GB Sequoia, M1 MBAir, 2012 MBP
Digital Performer11, LogicPro, Finale27/Dorico/Encore/SmartScorePro64/Notion6 /Overture5