MiSTeraddons.com has just listed a fully-tested power switch for the MiSTer platform: http://misteraddons.com/product/in-line-power-switch/
Most of the in-line switches people have been testing with the MiSTer have significantly dropped the voltage when put between the power supply and DE-10, causing performance issues. You’d think finding something as basic as a power switch would be simple, but this is the first time someone’s found one that performs safely!
If you’re like me and want to leave your MiSTer plugged in all the time, pick up one of those switches and make life easier! If you haven’t picked up a MiSTer yet, start with the DE-10 Nano and USB hub linked below and check out other items MiSTerAddons has to offer to upgrade the experience!