We finished our last MK2 transformer install yesterday.
Wow... Many flaws. All digital boards standoffs were completely loose. The bolt that holds the power transformer was not even tightened. It was moving around inside the case. The i2s inputs grounding tabs were not contacting the chassis, The ribbon cable to the display was resting on the power transformer, Three adapter boards were used on the SPDIF / AES XLR circuits causing a loud pop when switching from DSD to PCM. We have seen many of these adapter boards in customer units over the past 6 months.
These are just some of the reason we are no longer offering transformers for the MK2. We have found many other issues as well.
If you see these adapter boards in your unit you will have this loud popping issue.
Fortunately our unit we sold a few weeks ago did not have any of these adapter boards.