A quick scan of the DR-1 specs suggests its only inputs are analog: 1/8" stereo mic input and 1/8" stereo line input. So you'd have to run analog-out of the UA5 via the RCAs, using a dual-RCA > 1/8" stereo cable. Of course, ideally, you'd run digital from the UA5 to the DR-1, but it doesn't look like that's possible. Instead, the signal path will be mics > UA5 analog-inputs > UA5 ADC > UA5 DAC > UA5 analog-outputs > DR-1 analog-inputs > DR1 ADC > media.
'Course, I could be wrong about the DR-1, I'm not familiar with it first-hand.