This has way too much gain for Neumann KM184's.
Your ipad issue you mention in the FS thread makes sense if you don't have a powered hub to connect them through as
SD notes, but I'm calling user error on this one. You didn't post any additional information that was requested for us to help you and the specs for both pieces of equipment are well known:
KM184s are 14 mv/pa.
USBPre2 has a mic in clip point with the pad on of +4dbu. The limiter engages at -4dbfs.
Given all of this, with your usbpre2 set to minimum gain, it should not hit
the limiter (let alone clip) with the Neumanns until you hit a hearing damaging 129SPL (and they wont clip until around 133 or 134). That's really rare here in the environments frequented by those here on TS.com; on stage, spot micing, etc. Thats where you'll see those levels. Anyone standing virtually anywhere in the audience won't come close.
So sure, you can sell the unit, but the above quote is a crap blanket statement.