The Playback MPD-8 lacks the on-board streamer. That said, I had a customer do a direct compare (in-home demo) of the Bartok Apex vs the MPD-6 from Playback and he opted for the Playback. His perspective was that detail was a push but the staging on the Playback was superior. The MPD-6 has a streamer option you can add for $3k. MPD-6 with Stream-X is $18k.
I would look at the Weiss Helios, not the 501. The Helios is better in just about every way and is right in the same range as the Bartok in terms of price at $21,995. Incredibly detailed and some of the best instrument separation I have heard in any DAC.
I love the Chord but it is 10 years into its life cycle. Depending on how long you plan to keep it, or how upset you get about new gear coming out, this could be N issue. That said, I think Chord is one of the very best DACs direct into a power amp or powered speakers. The volume control/preamp stage is great but does not have a streamer built in.