Steve,
I don't have a full understanding of the way that DACs process a signal, but from what I've read a 96Mhz DAC processes at a top end of around 18 bits and a 192 DAC at some thing like 22-24 bits. The 192 DACs also have a designed in lower inherent noise floor shown as the DACs S/N ratio. The audible benefit of this is dependent on the full circuit design as well as the source material.

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Take Care,
merc