Hi Josh,

The microphone you purchased is a general purpose inexpensive mic. In the Microphone for vocals area unfortunately you always get what you pay for.
A $79 mic typicaly will not have a lot of gain but heres some things to check.

First, I recommend you check the battery in the mic make sure it's a good one and the polarity is correct. Condenser mics depend totally on the batterys condition ..hense bad battery no output.

Then check your Korg D4 and make sure you don't have an attenuator or pad in the line. Make sure the gain is fully open.

If this still does not solve the problem you need to get a better microphone. For extremely limited budgets I recommend a
Shure SM58 for Vocals or SM57 the no pop screen version of same as a good starter mic and it can also be used for live performance.

It's extremely well made and very tough and will last forever. Known the world over as an industry standard.
especially in the Live Vocal arena.

Street price around $150 if you check around and in it's price range hard to beat.

If you have more to spend let me know and I will advise.

your only a stranger once after that a new found friend
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http://www.LarryReadsMusic.com
Singer/Songwriter/Guitarist/Audio Engineer BMI &
Audio Engineering Society Member