I bought a Lumin D2 last week from Audio Doctor based partially on this and other threads and just talking to Dave, who was very helpful. I can’t really express how much I love this unit, it sounds amazing in my minimalist system, which now consists of:
Lumin D2 (running Tidal)
Clones Audio 25IRH
Harbeth C7es3
REL T5i
Was using a very well regarded NOS dac fed by an sms200 and the Lumin was definitely a step or 2 up. More everything - more detail, more overtones, more richness, more space, deeper bass with more weight and articulation and better timing. Been enjoying the Lumin app so far as I get to know it better. Way better than the mconnect I was using. Dave gave me a nice deal on a demo unit with the possibility of trading up to the T2 at some point as well. Super happy with this unit so I imagine the T2 must be pretty amazing, although must be a different flavor with the ESS dac vs Wolfson.