As standard as RCA interconnects; the standard for digital signals (okay, one of them but always a safe bet) is the 75 ohm, spdif connector. (looks like an rca female, but there is only one, usually labeled "digital out"). Rule of thumb is that its a better sound than the optincal "toslink" (tolink looks like a small plastic box, sometimes has a plug in it and transmits light (looks red if you peak in the small box). You connect the dac with a 75 ohm digital cable, not a regular interconnect. The premise is than in your denon, the denon reads the CD (transport section) and than converts from digital to analogue (DAC section), which is outputted through the RCA outputs (left and right). The DAC bypasses the digital to analogue conversion in the Denon to an outboard (hopefully better) converter. It will all work. DACs go by costs and individual preference of sound, techology (upsampling) but most attributed to the quality/make of the chip used in the dac.