http://torley.com/how-to-boost-the-mic- ... udio-codec
"My Asus P5K motherboard has an integrated Realtek ALC883 sound system: it's alright, but one of the glaring gaps out-of-the-box is that the microphone level, by default, it just too dang soft. What's even more frustrating is looking in Control Panel > Sounds and Audio Devices will show the mic volume as grayed out and unchangeable, when infact, it really can be amped up.
Here's how to boost the level, whether you're on this motherboard, or another which uses the same or similar audio codec:
* Install the drivers first. They will most likely be included on a CD-ROM that comes with your motherboard.
* After doing the mandatory restart, look in your Windows taskbar for the "Realtek HD Audio Manager" icon. On my system, it looks like a pixelated orange speaker. (Alternatively, you can go to Control Panel > Realtek HD Sound Effect Manager.)
Realtek HD Audio Manager - icon on Windows Taskbar
* Double-click that icon and then click the Mixer tab. (Now here's where you'll find yourself declaring, "Why didn't they make this more obvious?")
* See the "<" and ">" buttons on the top row, Playback? This is understandably unintuitive because the section's labeled "Realtek HD Audio output", when you'd expect to find the mic volume control in the input section — where it's frustratingly grayed out. Don't worry, keep clicking ">" until you see "Mic Volume". The first time you go there, the volume slider will probably be set at nearly the bottom. Drag that all the way up to the top. If applicable, you may want to do the same for "Front Pink In", which should correspond with the front mic jack on your computer's case.
Realtek HD Audio Manager - getting to Mic Volume
* After setting that, try test recording and watching the levels in your fave audio editor. Windows Sound Recorder is mediocre, so if you need to look at meters to gauge volume more accurately, check out Audacity — it's free.
* If that's still too soft, go back to the Realtek HD Audio Manager, and click the ".." button. You'll see this is where the "Microphone Boost" option is (on most integrated audio codecs like AC'97, it's found via the Sounds and Audio Devices control panel. Check it and click OK, and test again in your preferred audio editor.
* Optional: if you hear a lot of hiss and white noise when recording, you may find it helpful to mute non-active inputs. In the Realtek HD Audio Manager, in the bottom section, click the little speaker icons for "CD Volume", "Line Volume", and "Stereo Mix" so they've got red X's.
This is how I've got it setup:
Realtek HD Audio Manager - ALC883 - boosting my volume level
I've not verified this, but the above may also be applicable for the Realtek ALC861, ALC681-VD-GR, ALC880 Series, ALC882, ALC888, ALC888T, ALC885, and ALC888S, and maybe others too."