Me, I have, and still do
Before entering this rabbit-hole I'm going to preface all of this by YMMV, and we all hear things uniquely from one another, and have subjectively differing preferences from one another.
That said, I have both the SU-6 and the IRIS and swap them between systems from time to time. My headphone setups (as of today):
Home: macOS laptop --> SU-6 --> Gungnir MB A2 (BNC) --> Lokius --> Mjolnir 3 / Folkvangr
Work: macOS laptop --> IRIS --> Yggy+ GS2 (AES/EBU) --> Lokius --> Violectric v281 / Feliks Euforia / Woo WA2
Why, why, why would I put a DDC into the chain when everyone knows it's just oil of the snake
- I prefer to use AES/EBU or BNC as my DAC input when possible
- I stream from my laptop which is generally running/building/compiling about a dozen different things at any given time so the CPU/GPU loads are continually fluctuating in ways that "may" not be ideal for music via USB
My observations are these
- An overall cleaner and very detailed soundscape with a new openness to the music
- I originally thought the openness was a slowness, but it's more along the lines of being able to more easily detect the leading and trailing edges of notes that might otherwise blur together, so sonically it appears to be more space in the composition (if that makes any sense at all)
- The SU-6 is a bit more forward presentation than the IRIS
- The IRIS feels a bit more relaxed, but wider in it's presentation and staging
- Both the SU-6 and IRIS are equally detailed in what I can discern
- The differences were immediate, and for me preferable to not having a DDC in the chain
My foray into DDC-land was through the classifieds. I figured they hold their value well enough that if I didn't like what I heard I could always resell it without taking a big loss. If I were using a dedicated streamer that was on the same conditioned power along with the rest of my audio gear I might have a different opinion, but for now I'm keeping the DDCs my chains.
In the end only you can decide if a DDC is worth it or not, and as with everything in this hobby, there are many factors at play.