Bracing is important in that it keeps panel vibrations to a minimum. It is important that the cabinet not add sound of its own, and you should be able to strike the cabinet with your knuckles and not hear a resonant "drum head" sound. As mentioned above, the braces also serve to hold cross-section dampers, one a third of the way up and another a third of the way down. They should be cross braces or window braces and they should double as a place to hang partitioning pieces of insulation across the cross-section of the cabinet.