RE: Microphone volume is very low on a Dell inspiron 13 7348 with Windows 10
I found a solution that worked for me. I was part of the Windows 10 Insider Preview and had downloaded an audio driver when I was testing it out. Dell didn't have Windows 10 support at the time, so the driver is actually for Windows 8.1 systems and found here:
I didn't give the installer a try, but instead just extracted the files, then went into Device Manager->Sound, Video, and Game Controllers->Realtek High Definition Audio Device->Update Driver Software->Browse My Computer->Let me pick from a list->Have disk, then navigate to where you extracted the driver files until you get to the vista64 folder. Open that, click next, and it should roll back your driver.
It seems as though the Dell Audio Manager is no longer installed now as well. I have a feeling it tries to do something fancy with the mic settings but doesn't interface as well as they'd hope.