I got a chance to listen to a Bartok today, and while I was impressed, I wasn't that impressed. Unfortunately since it wasn't in my own system with my own power cables, source it wasn't an apples to apples comparison.
I found the Bartok to be extremely transparent, with almost perfect separation, control and balance, extreme detail and space, and a very wide soundstage. It was extremely good at conveying the music performance. On the other hand, it had an unpleasant glare that I really didn't like (seems to be from the ethernet), was a bit too clean, and the headphone amp was quite underpowered in single ended mode for my Meze Empyreans. I had to use the highest output setting and I was still having to set the volume around 80% or higher.
We swapped in a balanced Transparent headphone cable which greatly improved the sound. With the addition of a Transparent power cable things also got a lot better, and with Transparent ethernet it got a little better as well. This was getting closer to my own setup, but Transparent vs Shunyata NR cables, not having my Denali, and ethernet vs high end USB all confounded things a lot.
I came away feeling that actually the network cable and source really do matter in this instance, and that it won't be an opportunity to save money. This is a bummer, because not needing an expensive server and cables was a key point for me. Like any DAC, getting a decent sound seems totally dependent on power, cables, vibration control, etc.
When I came home I found that my own setup with PS Audio and MZ3 was richer with tonal color, better texture, more full in the low end, and didn't have that weird glare. The only other DAC I've heard that glare from is the Chord Hugo 2.
It seems like the best combination here is probably the Bartok with my own power cables, vibration feet, an upgraded fuse, and keeping the LTA MZ3 amplifier. Bartok was wider, but couldn't hold a candle to the MZ3 or The King in single ended mode with the 1/4" headphone cable I own. Even my Mytek Manhattan II performed better for unbalanced than the Bartok. Only with an $1800 balanced cable did it compete, and I feel like it still needed a little more power.