I do mods to various class D amps. Mostly I have modded the Purify based amps from VTV but have modded all the ones listed in the title. You can see more info on the mods and some pics at my website. The mods make the amps way more transparent and musical sounding. I have been modding and manufacturing high end gear since the 1970s. I have a sterling reputation.
The mods start at $500.....depends on the model...and whether it is dual mono or mono blocks.