Thunderbolt DAC input?

[barrows]

On 9/26/2018 at 4:48 PM, Panelhead said:

  Well, I have listened to a proper operating TB optical cable and a copper version. They do not sound the same. 

  The copper Thunderbolt is softer sounding. There is a more analog sound. Notes flow together. Much more musical.

  The optical cable is much more brash and dynamic. I would first say distorted. But listening reveals there are individual notes. Listened to a recording with what sounds like a nylon strung guitar. The attach and pluck emerges from a deeper silence. The notes explode from a deep black. Individual notes are portrayed where I hear flow with a copper cable.

  I have now moved the computer back to a spot where only the Corning cable will connect. I swapped back and forth three times. First round the Apple cable was preferred, second was a draw. The last comparison had me preferring the optical fiber. 

  The revealing nature I hear is not as pleasant. But is closer to what was I think was recorded.

  Do not know if the users of the Corning USB cables hear the same deeper silences and resolution as the Thunderbolt cable.

  One item I noticed is the connectors get warm. Not hot, but warm. After being powered for only a hour. The data rate is peanuts for a 10 Gbit interface. All files are are played at 192/24. This heat generated in the connectors may contribute to the short life span of the Corning cables. 

  

Sounds to me like you are experiencing higher resolution playback with the optical cable, and, thank you for your frank and sober reporting of your findings.  It is not uncommon, when a system tuned to sound "good" or "right" with lower resolution, that when the resolution is raised, it sounds "wrong", or perhaps too incisive, or as if transients are too sharp.  Sometimes all that is required is to get used to the new sound, or sometimes the new sound is really tonally off a bit, and requires some system tuning (often something as simple as adjusting speaker toe in) to regain "proper" or more "pleasant" tonal representation.  If one can get this right, one can have the higher resolution, along with an accurate/pleasing tonal balance.  In some cases, higher resolution may reveal system problems which need to be addressed at the component level as well (synergy problems, etc).