Definitely don't waste a dime on DAC.
Unless you have golden ears that claim to be able to hear THD of > 0.003% or SNR < 90dB, don't worry about any DAC in any AVR or Pre-pro.
Bottom line - don't worry about chasing DACs, CD players, Amps, Preamps, and Wires/Cables - they don't have a sound signature of their own (unless you have golden ears). Focus on Speakers and Processors (EQ, DSP) since they will sound differently.