Yes, we have a MK2 upgrade for the STM available. It decreases heat dissipation (KING STM gets pretty warm) and lowers distortion at mid-power. This upgrade is applicable to every STM built so far that has not already been converted to MK2. The upgrade is on sale until March 1st almost with a variety of Cherry amps, DACs, and USB-to-SPDIF converters. Email Support@DigitalAmp.com for the sale list. Thanks.