Paul, I am not sure what you are asking here. A compatible i2s port is just that, so point 1 has no meaning. It is either compatible or not and it would be the SSR that determines the quality as it is the transport. SSR uses the PS Audio HDMI LVDS i2s standard, ie LVDS protocal for i2s and PSA HDMI pinout which I alredy posted at the SSR thread.
Lukasz told me (when I asked a month ago) he has done it for PCM and knows that it works, but recall that the B7 is 2 "Dacs" in one box, PCM and DSD. He would need an actual unit to develop the DSD aspect of the HDMI port...to ensure flawless working and no clicks/pops either. One thing is the excange of specs, but another is a love unit to test all aspects of implementation. I would imagine that the single HDMI port could handle both (Lampi chipless) DSD and PCM...perhaps needing a switch. In any case, this HDMI receiver would shunt pure i2s data stream to the appropriate place in the Dac. i2s is the "native" internal language of Dacs.
Theoretically for all Dacs, the i2s cannot be inferior to USB, as it does not have the same baggage of the packetized USB data stream. The SSR has a bespoke conversion process that changes ethernet Data to i2s while blocking all the incoming crud and without creating new noise and thus true galvanic isolation is assured. In practice, the proof in the pudding is in the eating. i would expect that the SSR feeding DSD to the Lampi will way outperform the DS Dac, based on what I heard a year ago. Yes the DS is much improved in DS vs a year ago, but the gap was soooo wide, I still expect quite a distance between them (also based on the undesirable processing of DSD in the DS Dac). Also, the Lampi DSD has been a bit improved as well in the interim. JMHO
