I believe I was the first person to post about the Matrix X-SPDIF 2 on this forum. It was just over a year ago. At that time, I wrote:
“Preliminary impressions are quite positive – detail and sound stage/image focus have improved, without any noticeable negative effects…”
Since then, numerous DS owners/forum members have purchased the Matrix. I have lost count of how many people have PM’ed me to tell me how much they enjoy the Matrix.
My understanding is that the DS Sr. performs a USB-to-I2S conversion INTERNALLY. In theory, performing the USB-to-I2S conversion EXTERNALLY should sound worse, e.g., because an external conversion introduces another cable and power supply into the equation. But for whatever reason, the external USB-to-I2S conversion via the Matrix makes thing sound better – much better by my and many others’ assessments – than running USB into the DS directly.
In my case, I was using a $649 Revelation Audio Labs dual-conduit USB cable from my Melco N1Z (Mk. 1) to the DS Sr. I now run the Revelation USB cable from the Melco into the Matrix, and I use a dirt-cheap HDMI cable from the Matrix to the DS Sr. This setup sounds like a different and much more expensive DAC than running USB direct from the Melco to the DS Sr.
By the way, adding an external PSU to the Matrix makes it sound even better. I currently use a 5v iFi iPower PSU, which made a nice improvement over running the Matrix on USB power. A forum member who bought a Matrix in part on my recommendation PM’ed me recently to say that he got a massive bump in sound quality by adding an UpTone UltraCap LPS-1.2 PSU to his Matrix. I am thinking about picking up an UpTone, myself.