WELL - since there are now TWO of you asking 
I am going to take the lazy way out and copy and paste. Since Naim does not allow private messaging on the forum - but dCS does - I have had a few exchanges with Dunc to find out how he is doing with his new Rossini.
I have had the Bartok here for exactly one month. Below is a copy of my initial exchange with him and details of my month long journey. Please keep in mind that my 552/500 is currently away and undergoing both recap and DR. In other words it is impossible for me to demo via my Naim system - and really not necessary (at least initially) as the Bartok was purchased for use in a separate headphone system in my bedroom (* this may now change). The Focal Utopia headphones are like any great speaker - they are easily capable of showing any changes made to the source.
In a nutshell I could easily live with the Bartok for what I want to use it for. Unfortunately there is also better - and I tend not to know when to stop until I arrive there.
More to come.
Best
Gregg
I have been using a Linn Klimax DS in my Naim system since 2011 always upgraded to current specification. When I made the move to digital from a CD555 Naim had only released the unimpressive HDX. The NDS had yet to be released. I and many other Naim forum members at the time migrated to Linn and have not looked back.
The Bartok was never intended to replace the KDS in my system but rather be used in a new stand alone headphone system in my master bedroom. It looked like an interesting solution being an all in one streamer/DAC/headphone amplifier. Past CanJam headphone shows in NY allowed for demos of the Chord TT2 and Dave - both sounding thin, lightweight and uninvolving. I was able to have a Bartok demo at a local shop followed by a second demo at CanJam . I felt comfortable enough ordering one “pre Covid” and it was shipped prior to dCS closing. It has now been here for one month.
Please keep in mind that my impressions are based exclusively listening to the Bartok via headphones - specifically Focal Utopias. This was the original reason for the purchase - headphone listening. On a side note my 552/500 are currently at Chris West’s for a 15 year recap and DR so I am unable to listen to the Bartok in the context of my Naim system.
After allowing 100 hours of burn in I spent one week listening to the Bartok via its internal headphone amplifier and then another few days comparing it to my Klimax DS through an external HeadAmp GSX Mini headphone amplifier. What I found was that the Linn beat the Bartok - expected when considering the cost differential. Not a fair comparison financially HOWEVER the Bartok did amazingly well and imho can be considered incredible value for money and almost a giant killer based upon its price/performance. I would score Bartok 88 Linn KDS 100. As usual with HiFi an exorbitant amount of money would be required to obtain the last 10%. The Linn still had more detail, sounded more real with greater air and room around instruments and voices. It also has PRAT and involvement.
My problem was while the Bartok was meant for casual listening in the bedroom my ears remain used to the Linn’s high level of performance. My initial thoughts were now to think about sourcing a second KDS preloved from my dealer. I immediately started doubting the wisdom of having TWO Klimax DS’s. It was then that a new thought entered my mind and musings about a Rossini started to take place. The thought was since the Bartok was offering up such respectable performance at its price a Rossini had a real chance of actually beating my Linn. I started contemplating the possibility of owning both and swapping them every 6 months between the headphone and Naim 2 channel system. A different flavor of the month when the mood desired.
I then had an interesting discussion with my dCS salesman (who previously sold Naim/Linn) and discussed some of my Bartok concerns and he then suggested I conduct an experiment. Leave the interconnect cables and HeadAmp GSX amp as the constant and compare strictly the Bartok as a DAC (no headphone amp) vs. the Linn KDS DAC.
This new experiment has just ended and the results were very interesting. Where as before it was Bartok 88/Linn 100 I now see it as Bartok 95/Linn 100. It appears to me that the Bartok’s internal headphone amplifier was holding back the Bartok’s DAC resolving capabilities. Now the Bartok EASILY had detail, realism, air and space which made it a worthy competitor to the Linn - and now extremely impressive at $13.5k vs. $24k.
What I would be interested in hearing from you is your thoughts on the Bartok vs. Rossini and what differences you are finding between the two. Now that I have been able to hear the Bartok strictly as a DAC I have found that it perhaps surpasses the Linn in rendering detail, weight, sparkle and air. The main place where it lets me down is in those mythical qualities of Naim PRAT, timing and INVOLVEMENT. I seem to recall you posting on the Naim forum about the hairs standing up on your body when you listened to the Rossini. That is what I am missing from the Bartok. Previous dCA boxes have been accused of being ultra detailed and resolving yet missing PRAT and involvement. I believe with the new Bartok and Rossini 2.0 dCS have now changed direction. Actually the internal headphone amplifier of the Bartok seems to flavor the proceedings with a slight bit of PRAT - although this comes at a slight loss of detail, resolution, air and space.
So in the end I my question is how have you found the PRAT and timing of the Rossini? Compared to the Bartok is the bass more driving and rhythmic, are your toes tapping more, does the band sound like they are playing together and in a groove? I am sure you completely understand the questions I am asking as this is exactly what we get from our Naim systems - perhaps you even more as you have been using a Naim NDS as a source while I have been using my Linn. Is the Rossini more Naim like than the Bartok? Does it give you the Naim PRAT of your NDS - does the excitement listening to music make the, to quote you, the hairs stand up on your body. I need to figure this out if I am to embark on an even larger financial investment.
I look forward to your reply - and unfortunately I also assume you will mention the elephant in the room which I have not written about above - the Rossini external clock! While I welcome your comments about it as well for now I need to focus on hearing your feedback about a stand alone Rossini. The icing on the cake is optional and can come later.
