Scott,
I first hooked the rDAC to my Rotel RCD991AE cd player via the coax ouput. It really improved the sound immediately. I remember the Wolfson 8741 DAC being warmer. The irDAC with the Burr Brown 1796 DAC has more detail.
Connectivity is better.
2 coax inputs (instead of 1)
2 optical inputs ( instead of 1)
Still incorporates the USB
They added a coax output and a remote.
Im currently borrowing a Arcam CD93T from a friend. It has 24/192kHz upsampling and 4 Woflson 8741 DAC's per channel. It is smooth. Hope it helps.
N