Not only does it need balanced XLR inputs and outputs, the circuit topology needs to be 100% balanced from stem to stern.

It should also be able to switch from two (or three) 6-8 channel discrete devices since many people have separate DVD-Audio and SACD players.

Zero loss signal path with no audio coloration. This demands the best power supply, circuit boards, capacitors, filters, ultra high bandwidth designs, etc.

Analog bass management with no ADC.