This is a very interesting topic that generates a wide variety of opinions from audiophiles. My personal experience with balanced signals has generally been favorable, particularly in regard to hum and noise rejection. The sonic differences are often quite subtle, and equipment must be designed appropriately to provide the full benefit. Many units offering "balanced " outputs simply use an additional op amp to create an inverting output, and this can actually degrade the sound. True balanced differential operation for 8 (7.1) discrete channels would require 16 separate paths for amplification, volume control, and (hopefully) D-to-A conversion. Another possibility would be the use of output transformers to galvanically isolate the signal, but that would also be an expensive solution requiring 8 discrete transformers. It would be distinctly unusual to find either of these approaches utilized in an inexpensive preamp/processor, but maybe the Outlaws have pulled it off. The Outlaw M200 amplifier is an example of true balanced differential operation and is among the least expensive quality amplifiers on the market. It is a shame that an XLR input wasn't provided to take full advantage of the design. As for the 990, perhaps someone in the know can provide the answer?