I didn’t realize that it had a low impedance - how would that affect the sound?Compared to output impedances that are considerably higher (as is especially common among tube-based preamps and source components) it will to some degree lessen sensitivity to cable differences, and also to sonic effects that might otherwise result from interactions between that output impedance and amplifier input impedance. So to at least a small degree it works in the direction of improving the accuracy and neutrality with which signals are conveyed from the bluMe to the Wadia.
My assumption was that the Auris wouldn’t have the DAC in the path of the analog being an inexpensive device - but I have no idea.Since Bluetooth conveys information in digital form it is the analog output of the bluMe rather than the optical output that would have the bluMe’s internal DAC (digital to analog converter) in the signal path. However, although optical interfaces are digital they have tradeoffs and potential downsides of their own, so the only meaningful way to compare the two approaches is to try them both, as you’ve done.
In any event, I would still suspect that trying to use a cable to compensate for the shortcomings of a $169 component providing DAC functionality as well as Bluetooth functionality, and having low output impedance, is not likely to be fruitful. And I would consider the relevance of cable recommendations which are provided based on experience with very different and presumably higher quality applications to be questionable at best.
Good luck, however you decide to proceed. Regards,
-- Al