Spdif out to XLR

[Axel]

A precision to my answer above: It only applies to the DAC part. I have no idea about the quality of the Headphone Amplifier you are using compared to the amplifier of the Devialet, especially at the very low power needed by a headphone. So if you are reliably hearing a difference (ABX) it is likely more due to the amplifier than the DAC part.

Thanks @Jean-Marie.
I’m being a bit picky in needing to get rid of the 50Hz hum as it doesn’t impact on the music at all. I suppose I’m really just wondering whether using another connection method will wring the last drop of sound out of my HD800s.
They are a heavy load at 300Ω and my Auralic Taurus hasn’t got enough grunt to drive them in single ended mode. In balanced mode I still have to set the volume on the amp at about 80% and control the output volume using roon but the sound is very good to my ears.
Firstly, I’m going to make a custom cable, as @hardcore suggested because I think it’s the cheapest option and easy to achieve.