@topside3 All 3 of my streamers were great. I have not heard the very best feature of the PlayBack Designs Streamer-IF because I do not have a PD DAC to use the PLink feature. However, the SPDIF of the IF sounded a mix in-between the Lumin X1 fibre and my Sonore OpticalRendu.
The Lumin X1 is as loud as the IF (just a gain setting I guess). It sounds the fastest on music playback. A real toe tapping experience. I loved the X1 streamer and the features on it are the best of all 3. This was very important when I wanted to stream to SPDIF to my incredible modded Peachtree GAN1. This GAN1 was as good as $20K+ gear with the Lumin X1 via SPDIF.
The OpticalRendu wsa not as loud and maybe not as fast sounding. It sounded rather refined to me compared to the other 2. The PD IF was in-between the sonics of the OpticalRendu and the X1. I think if I got the Plink hooked up (in the future) it likely will have the best streaming sound or experience. At the moment I think my OpticalRendu is my fav. Though it is like choosing between chocolate and vanilla, both are very good and a matter of taste.
I was surprised that these 3 high end streamers would have such a variety in sound. I have used lower end streamers and they do not compare to the X1 and oR in terms of details and other sonic attributes I value.
Note: I only used the X1 with a fibre input stream