Regarding the remote POWER ON of the KPA-500 amplifier, in going over the tech manual it appears you can turn on the amplifier by taking the aux connector pin 8 low, but only for a moment, do not hold low. I've attached a scan of the AUX connector interface pinout. Note it is a DE-15 Male plug. So... I will try using a pair of extra contacts on my webswitch to pull that pin low and see if it turns on the KPA. Otherwise I will have to leave ON in STBY all the time.
//dave WB7ELY