That doesn't sound right. I'd go back in there and make sure you can do the sound test. Even with a 2.1 setup (dedicated mains and .1 from the 7.1) I was able to run it and test all three speakers.
I do not understand this. I'm using a subwoofer with crossover processing enabled and I hear no need to increase the output boost of the subwoofer. Is this just the situation with the balanced outputs?