Due to the XLR shield and ground pin specification (see https://en.wikipedia.org/wiki/XLR_connector), some manufacturers implement it differently from others, therefore there could be humming noise if a non NuPrime product is connected to MCH-K38 using XLR cables.

XLR Hum Eliminator products from http://www.ebtechaudio.com/hedes.html can be used to completely remove the noise and improve performance.