No SSD inside. I use a small external SSD on each on them for use with MPD. It will also connect via Tidal, Qobuz, and something from Bryston called B-Radio. (ethernet connection).
IMO, Bryston MPD sounds better to me than Roon RAAT. The Manic Moose firmware is much less refined than Roon.
The BDP-2 with IAD is nearly as good sound quality wise as the BDP-3. One catch, you have to buy one made in the later half of 2015 or later, or buy an upgraded one. The early BDP-2s used Juli cards and were souped up BDP-1s with better memory.