For the Diablo, consider having it adjusted to run with 240V and running 12/2 Romex instead of 10/2. Using 240V / 20A circuit the Diablo 300 will require a 6.3A fuse, which leaves a big ratio between circuit capacity and amp needs of about 3:1. This ratio is actually a bit better than you'd get with 10/2 at 120V: 30 Amps possible / 12A needed, so closer to 2:1
In addition, running 240V the voltage drop will be halved for the same distance given the Diablo 300. A much stiffer situation.
Best,
Erik