Perhaps most would just get a good TRS to TRS cable and strip one end, but the amp's user guide has a "do-not-attempt-this-at-home" warning about wiring. I don't want to fry anything.
I did find a TRS to stripped wire cable on eBay,
https://www.ebay.com/itm/353255077773 made by Philmore.
http://lkgind.com/CatalogDetail/33250I don't know this manufacturer and I was hoping for something much shorter. $24 for 4 with free shipping seems pretty cheap, and one of the reviews is not encouraging.
The user guide also warns that Class 2 wiring is required. I'm not sure what that implies.
More comments? Hauptwerk is hard enough. This shouldn't be!