I have used mirage and an older preamp with my 847, but not powered by the rf ports. I must admit I did smoke the non mirage through complete absent minded issue. I was trying to play with arecibo on 432 (read excited) and plugged in the digital stuff to the 1/8" radio port while all were powered. When one of the rings shorted, radio went to transmit at full power which killed the preamp. Also be aware 847's have nasty habit of a very short full power burst at powerup on what ever band you happen to be on. Not wanting to trust the rf control part of the mirage preamp, I run direct hard control using the amp control signal port from the radio.