I would use the digital output with an audio coax cable.You might find that the DAC helps even more if you obtain a cable that is specifically intended for digital applications, meaning in particular a cable that is designed to have a 75 ohm "characteristic impedance". With a cable that is designed to carry analog audio signals chances are good that impedance mismatches between the cable and the components will adversely affect sound quality, by causing reflection effects that degrade waveform quality and result in increased jitter (timing fluctuations) when the digital data is converted to analog.
Also, I suggest that the cable be either 1.5 meters or slightly longer (i.e., 5 or 6 feet), or very short if that is practicable (i.e., about 8 inches or less). More often than not intermediate lengths, such as 1 meter, will not work as well, although that is component-dependent. See this paper.