There is no interference between channels because of the separate power supplies and separate chassis.
Mono amps can be put behind the speakers with very short speaker wires. This minimizes speaker wire loss.
Two smaller chassis are easier to move.
(Quicksilver amps are heavy!)
Even when placed side-by-side and used like a stereo amp, you retain the advantages of mono amps.

The input sensitivity of all Quicksilver amplifiers except the Horn Mono is in the range of 1 to 1.5 volts.

At Quicksilver we believe very strongly in KIS – Keep it simple! Balanced inputs require extra circuitry in the signal path – circuitry that we believe gets between you and the music. There are applications for balanced inputs in the recording industry where noise becomes an issue when using long cable lengths with low level (microphone) signals. Also, some systems require balanced circuitry because all other components are balanced. Quicksilver can make V4 amplifiers in balanced configuration for these circumstances.

We recommend you keep it simple. Use simple cable geometries, high purity copper or pure silver, shielded interconnects, and keep your speaker wire as short as possible.