@bergenma
Great questions that probably bother silver disk fans!
I bought a Reavon UBR-X200 on a whim after my Marantz Universal Disk Player (UDP) carked it. Just went to a couple of HiFi shops nearby, The first told me I did not want to play SACDs (I have hundreds) and the second had just taken delivery of their first Reavon, which I had never heard of. I bought it anyway, because functionally it appeared to do everything I wanted.
There was also the Reavon UBR-X100 but it did not support SACD at all. The UBR-X110, which functions as a SACD transport, had not reached the market at that time.
My main left and right channels were played through Quad electrostatic speakers (2905) powered by a Krell class A amplifier (KSA-80) with an 18" Velodyne subwoofer.
My Reavon is connected by one of its HDMI outputs to my Audio Visual (AV) preprocessor, a Marantz AV8802. The Marantz tells me exactly what is being input including the connector, format and bit rate. The Reavon absolutely can output DSD 5.1 (Direct Stream Digital) natively over HDMI, as well as PCM from Pure Audio Blu-rays, Dolby Atmos, etc.
I also hooked up the seven analog output pairs to the Marantz using RCA connectors, as well as the two channel analog output using balanced XLR connectors.
The HiFi store promised me that CD playback would be as good as my venerable Sony player over balanced XLR, that Pure Audio would be as good as my old Marantz UDP, and that SACD analog output would be as good or better than the Marantz.
No problems with CD and Pure Audio playback, but when I switched to SACD I got full volume white noise (or pink?). The manual was wrong! Once sorted, the multi-channel SACD sound was way below what I was used to. I checked the specifications of the two-channel and multi-channel Burr Brown DACs. Neither mentioned DSD which is a good indication they cannot natively process DSD. I wrote to Reavon and they confirmed multi-channel DSD is down converted to CD quality PCM.
The two-channel Reavon DAC has better specifications, so I thought 2-channel DSD might be down converted to a higher resolution PCM but no, still just CD quality. No review that I have read mentions this, but to me the poor sound quality was almost instantly apparent.
My Marantz AV8802 on the other hand has 8 AKM 2-channel DACs similar in specification to the ESS Sabres used by Oppo. They process DSD natively. Using the Reavon as a pure transport works a treat when the Marantz is doing the analog conversion.
By the way, changing the output formats on the Reavon is painful: the machine has to be restarted. Now I just leave it on HDMI output, no problems.
I don’t know how good the Reavon UBR-X110 is - the power supplies are not as advanced as the X200 for a start. The addition of a 3-mm thick steel baseplate makes both machines feel like quality though!
There are other derivatives now on the market including Magnetar which use the same Mediatek System on a Chip (SOC). I believe Cambridge Audio has one as well. Pioneer seem still active, as is Panasonic but pride stops them offering rival Sony’s SACD format! There was also a Chinese-brand but I have forgotten its name.
I have a couple of very cheap Sony UDP transports, but I have not done a direct comparison. I suspect they are just as good, sonically.
Does I2S support multi-channel DSD? Until recently I had never heard of I2S which dates back to 1957.
My final thought is that the value-for-money offered by big manufacturers like Sony and Denon/Marantz far exceeds what niche manufacturers can offer, unless they piggback on others R&D, such as the Mediatek SOC.