balanced outputs

Krell also offers CAST outputs. But, to me the best thing about balanced is that it cancels hum.

Balanced inputs do a great job of reducing extraneus hum in your system (especially if you live in older digs where electrical shielding of cables in the walls is practically non-existent!) because of its unique cancelation characteristics. And yes, there is a dB gain, though it is not always 6dB (you can measure the gain with some basic lab equipment to determine the veracity of this statement).

It doesn't make sense not to use balanced interconnects. True balanced circuit designs should be used in every high end system. Balanced circuits would put the high $$$ snake oil cable salesmen out of business.
Designing true balanced preamps can be difficult to do because of the volume control.

Ivyinvestor, what electrical shielding of cables in the walls are you referring to?

It really depends on your components. If they are all truly(!) balanced, then this is the way to go. Many, if not most amps with balanced inputs are not really balanced and they add a circuit to conform with the RCA input.

Balanced and RCA interconnects can sound just as good as another. There is no problem with RCA at all Balanced is just less prone distortion and a better circut. If your going high end and or you have long runs to your amps I would invest in balanced. Most cable manfactures sill change the ends of your cables from rca to balanced for a small fee.

Again there is confusion between a "balanced" interface, and "complementary" circuitry. Complementary circuitry may have unbalanced input, and vice versa.

Balanced interconnects avoid noise pickup in the wires, and only in the wires. But, for any decent single-ended interconnect, of reasonable length, and outside of a bad environment (like being bundled with other wires) there is no significant noise pickup in the wire.

FWIW I do use balanced wires out to my power amps, which are 25 feet away from the source, but this is just because the electronics happen to have balanced interfaces. Results are no different from when I used single-ended interconnects with these same electronics.