[TenTec] Headset MIC connection ?

[Rick - DJ0IP / NJ0IP]

OK, I have this headset and I am trying to determine how to best connect the
mic to my Eagle.

I recall when I first got my Orion years ago, I had to separate the mic
negative from the shield, in order to prevent ground loops.

What worries me is, the headset's mic plug has 3 connections:  
 1) mic
 2) +Voltage
 3) ground

However in the meantime I thought the (Ten-Tec transceiver's) mic needs 3
connections itself:  
1) mic
2) mic negative (or mic ground) . . . separate from the shield
3) shield ground

So if my mic on my headset has only 3 connections and one of them is for
+Voltage, how do I prevent ground loops?

I want to build a breakout box (metal) with jacks for the headset mic and
headphones, but that will automatically connect the two grounds at the box.
Or is it indeed better to use a plastic box for this?

Is this metal box going to cause problems?

Normally I just let the key do the talking, so I don't have this kind of
silly problem with ground loops.

73
Rick, DJ0IP