Hi John,
Yes it’s a micro-toslink on the Brix (same connection socket as micro audio) and I haven’t used it so can’t speak from experience. I too understand that toslink often has that resolution limitation, but can’t confirm whether it exists here.
I’ve had no issues using my Brix after setting it up, but would counsel caution about making decisions about a new Core before deciding exactly what it is you want it to do. In particular the forthcoming integration with HQPlayer opens up a number of processer intensive possibilities that might affect hardware decisions.
Running RoonServer does not require huge processor resources and any modern i5 Brix or NUC will give snappy performance. If, however, you want that machine to also do real time upsampling (particularly to DSD) with HQPlayer and/or do real time room EQ using a convolution engine, then you would be better getting a powerful quad core i7. Some of the filters in HQP can tax any available consumer level hardware. (Beowulf cluster anyone ?)
Brian has indicated that HQP need not be running on the same machine as Roon Core. I understand that HQP will be a kind of network zone and users can send Roon output to HQP input using a network address. That enables some flexibility of hardware architecture whereby RoonServer could still operate on a dedicated lower spec machine and HQP could reside on a higher spec machine elsewhere on the network.
It may be that you have no interest in upsampling, real time room EQ, HQP or other possible future integrations, in which case all of the above is irrelevant, but I thought I’d mention it just in case because hardware decisions can be constraining.