Non oversampling would be when the DAC chip is run purely at the native sample rate - for CD that's 44k1. This rules out use of any 'low-bit' DACs, so the DAC would need to be a native 16bit part to do justice to RBCD.
Treble droop is inherent to the DAC part because the reconstruction is done with a ZOH - zero order hold in pretty much all DAC designs. So even with oversampling there will always be some droop, its just a matter of degree and NOS gives the biggest droop.
Images don't 'fold back' that's only with aliasing, not imaging. Aliasing is for ADCs, imaging for DACs.
Treble droop is inherent to the DAC part because the reconstruction is done with a ZOH - zero order hold in pretty much all DAC designs. So even with oversampling there will always be some droop, its just a matter of degree and NOS gives the biggest droop.
Images don't 'fold back' that's only with aliasing, not imaging. Aliasing is for ADCs, imaging for DACs.