I have 3 of these and can confirm that they are MBHO caps. They are stamped with 'KA' and 'Made In Germany' inside.....still looking for a pair of omni caps for these. Anybody? They have really strong gain, low noise and are extremely detailed. And if you are looking for something discrete, look how small they are.
Not sure I would describe them as Audix's version of MBHO. I believe Audix designed their own preamp internals for these mics and so they apparently sound quite different. I suspect, with some ignorance and no experience in support, that the MBHO preamps are a bit better. In fact I started collecting the SCX-1, as they were so cheap, with a view to buying the MBHO 604 preamps for the capsules. They cost me $600 for all 3.