[BC] Mic impedance question...

[Glen Kippel]

I am putting together a basic recording setup to do my audiobooks and possibly some voiceover work and have a question about the load impedance presented to the mic.  Most of the mics I have been looking at show an impedance of 200 ohms (a couple are 75 and one is 50 ohms).  But the only mics that specify both their source impedance and a recommended load specify that the load impedance should be 1000 ohms or more.  The problem is, just about every mixer or USB adapter that I have spec'ed lists an input impedance of 600 ohms.
 
Could this be detimental to the sound I am attempting to achieve?  I am kind of thinking of putting a dual, linear 1-K pot in a Bud box along with the appropriate XLR connectors so that I can set the load impedance to the recommended value.  Any comments or suggestions?