\rHi Will:
You have an interesting setup with your entry-level 7.2 SONY STR-DH790 and Definitive Technology Speakers. The AMP300 is a good choice because of its High (Speaker) Level input option. But you would need two of them, one for the pair of BP9080X connected to the Front Right and left speaker output of the SONY. A second AMP300 would be connected to the surround channels of the SONY AVR. The SONY Receiver would drive the Center Channel while the SONY's channels 6 and 7 would connect to the DOLBY ATMOS speaker input of the Def. Tech. PP9080X Front Channel Tower Speakers. You will need to use a Y adaptor for each Subwoofer output to connect both Front BP9080X LFE Input to Sub 1 output and then connect Sub 2 using a second splitter to connect to the LFE input on both BP9020. Otherwise, you could upgrade your SONY STR-DH790 to a Yamaha AVENTAGE RX-A4A, which features Preamp outputs for 7.2. Unfortunately, Sony does not offer a current model 7.2 AVR with Preamp outputs. I recommend our XA7180 with 130 watts per channel, all channels driven. You could increase that to 180 watts per channel, only using 5 of the 7 media while connecting the height speakers to the Yamaha directly. Please let me know if you need further clarification (tim@osdaudio.com).
TimL 6-5\r