One of the drivers might be out of phase with the other, ie. wired up backwards.

Any pot will still make crackling sounds with enough DC across it. Try putting a capacitor in there for AC-coupling, and see what difference it makes.

If 16mm is small enough, then TKD 16mm audio pots are very highly regarded, although I've never wanted to spend that much myself (about twice the price of an alps RK27).   If going for 9mm, then Alps, Bourns, Vishay are all pretty good imo. Just make sure to get the proper audio 'A' taper.  ...

Page 20 & 21 of this thread have some

Pretty sure all of ipads are usb audio class 2 compliant, and will support 24/192, the lightning based ones certainly do. You might need to use a USB hub after the camera CC, otherwise get the "this device uses too much power" error. 

Tip & Ring both to +ve Sleeve to ground

All the things you shouldn't do with a microwave are always the most fun.

Well I'm all out of ideas now. Good luck eliminating this gremlin.

This sounds like there is DC current across the pot, which would be due to the DC-offset from your source. A film cap on each left & right input leads, before the pot will AC couple them, and should get rid of the scratching. 2.2uF would be my preferred value for a 50k pot, but anything...

Gainclone is a speaker amp, not headphone amp

B-spec opamps are either higher binned, or specifically trimmed for better DC specs. AC performance is what matters for audio. For typical audio applications, I can't see a valid reason to pay the extra, go with A-spec.

You would need a ratchet crimping tool, with the correct sized hex die for the SMC connector.   Crimping of coax cable is pretty standard, but using normal stranded wires with a crimp connection designed for the shield of a coax cable won't be a guarantee for a secure connection anyway.

Skylar,   How much does the Nighthawk's performance suffer when driven from higher impedance (resistive) sources? Is there a significant/noticeable boost at low or high frequencies in output level or THD when driven from 10 ohm or 33 ohm source?

A single button remote is just a momentary switch shorting out between mic & ground.

1: Shield 2: + (non-inverted signal) 3: - (inverted signal)   yes wire 1-1, 2-2, 3-3   The casing for the xlr connector will usually also have a solder tab, better to leave this disconnected IMO.   More than you ever wanted to know about balanced connections. http://www.rane.com/note110.html