I went through this process 5 years ago. I wanted a preamp that went into Home Theater bypass mode while in standby mode so I didn’t need to do anything when engaging the AVR. I also wanted a preamp with good bass management since I share two subwoofers with the stereo preamp and the AVR. I narrowed it down to the Anthem STR and a Parasound P6 and bought an Anthem STR. A nice bonus was the STR’s very good MM/MC stage.
Since I use external amplifiers that are shared between the AVR and preamp and the amps are turned on and off via 12v triggers from both the STR and AVR, I needed to figure out a way to accomplish that without back feeding the 12v trigger to the idle device. Building a simple 12v Y-cable with a couple diodes solved this issue perfectly.