NETWORK-ATTACHED DAC

Network-attached DAC with optional headphone amp
Made by: Data Conversion Systems Ltd, Cambs
Supplied by: dCS LtdTelephone: 01954 233950
Web: www.dcsltd.co.uk
Price: £19,000 (£21,500 with headphone amp)

dCS Bartók APEX
Debuted in the flagship Vivaldi, and now trickled down to the Bartók, dCS’s APEX
upgrade brings enhancements to the PSU, Ring DAC clocking and analogue output
Review: Andrew Everard Lab: Paul MillerMaybe it’s a sign of the times,or the state of the specialist
high-end audio market, but
this latest version of dCS’s
Bartók streaming DAC, often referred to as
the company’s ‘entry-level’ model, is now
almost twice the price of the original [HFNMay ’19]. Then, the Bartók was £9999,
or £11,999 when fitted with the optional
headphone amplifier; now the Bartók
APEX, taking on board the company’s latest
package of enhancements, first seen in
the Vivaldi APEX [HFN Jun ’22], is £19,000,
rising to £21,500 if you choose to take theheadphone option.
Given this, and the performance onoffer from the APEX upgrade package as
already experienced in the Vivaldi APEX,
expectations are necessarily high for what
the new Bartók might bring to the digitalaudio party. Nor is this the first time thismodel has been upgraded in its relatively
short life. Last year a major software
update – Bartók 2.0 – included an upgrade
to the mapping algorithm controlling thedCS Ring DAC, improvements to the DSD
upsampling, and new digital filter options[see PM’s boxout, p49].

summing and output stages of the DAC.
The symmetry of the summing stage has
been improved, individual transistors on
the DAC board have been replaced with acompound pair, and the balanced analogue
output stage is, well, new.
So, it’s apparent that, while the Bartók
looks the same as always, these are far
from running updates. And the goodnews for existing Bartók owners is that anupgrade package can bring their players
up to date, albeit at a cost of £7500. That
headphone amp option, by the way, is only
available at point of purchase as it requires
a different faceplate configuration. And
while the original Bartók we reviewed
almost four years ago was supplied withthe headphone stage installed, the APEX
version we have here arrived ‘naked’!
Otherwise, the Bartók APEX is repletewith connectivity [see p51], including AES/EBU XLRs, which can be used separately

The inside story
Now the Bartók gets the full APEX package,
which isn’t a new digital-to-analogue
conversion technology – no matter what
you may have read elsewhere – but rather arethink of the power supplies, the clockingof the Ring DAC and improvements to theanalogue output stage.
To go into slightly more detail, though
the basis of the conversion remains
the same, the only element of the DAC
hardware that’s unchanged is the resistor
array at its core. The main DAC PCB
has been redesigned and re-laid, as has
the reference supply that feeds it, andthere are enhancements to the filter,
RIGHT: Screened transformer [blue box] andupdated PSU [lower left] feeds new generation
APEX Ring DAC, the latter including two Xilinx
processors and 2x48 element matrix [lowerright], and balanced audio output [top right]

Reprinted from Hi-Fi News for global distribution | www.hifinews.co.ukor paired to accept PCM data at up to384kHz, dCS-encrypted DSD, or DSD in DoP
up to DSD128. Then there are S/PDIF inputs
on RCA, BNC and optical plus a choice oftwo USB inputs – one a galvanically isolated
USB-B for computer connection, the othera USB-A port to accept music from storage
devices of up to 32GB. There are also wordclock inputs for the Bartók to be slaved toan external clock source.

Complete package
For many users – and count me in on thisone – the most attractive feature of theBartók will be its ability to operate as acomplete network-connected digital player
via its galvanically isolated RJ45 Ethernet
port. Here music may be streamed from amusic store on the home network, at up to384kHz PCM and DSD128, or from online
sources including Qobuz, Spotify and Tidal,
with full MQA decoding for the last ofthese. Internet radio is also available, andyou can even play music from your phone
via Apple AirPlay, though this latter facility
is well into ‘sledgehammer cracking a nut’
territory. Finally, the unit is also Roon-ready.
Control for all this network capability
is provided by the excellent dCS Mosaic
Control app, for Android or iOS, available
free from the usual online app stores. Thisworks in conjunction with the Mosaic
Processor software running on thehardware, and provides ‘palm of your hand’
set up and control of the Bartók. In use it
proves preferable to the minimal buttons
arrayed across the front of the unit, andthe often-complex menus they access.
Both balanced and unbalanced
analogue outputs are provided, with theability to use the DAC into a preamplifier
at a maximum fixed output of 2V or 6V bysetting the volume to ‘0.0dB’. Alternatively,
it can be run straight into a power amplifier
using the very high-quality volume control
and buffered output to bypass a separate
preamp altogether.

Consistency kingFirmly in the ‘hours of harmless fun’category is the raft of other adjustments
the Bartók APEX provides, including threesettings for the ‘mapper’ controlling how
data is served up to the Ring DAC, and an
extensive array of filter options for both
PCM and DSD [see PM’s boxout, below].
Having played with them for a good while,
I found myself reverting to the default
settings with either Filter 1 or 2.
Used both as a DAC/preamp andas a straight DAC into a conventional
amplification system, and over a variety

RINGING THE CHANGES
When it comes to digital filters, hi-fi brands typically fall into
one of two categories – those that ‘voice’ their product(s)with one type of filter (a variant of linear or minimum
phase, apodising, hybrid, etc, that’s either home-grownor baked into an off-the-shelf DAC) and those that open
the field with a smorgasbord of coefficients. Dependingon your viewpoint, multiple filters are either manna fromheaven for hi-fi tweakers, ambivalence on the part of thebrand or a crafty attempt to drive me around the twist by
exponentially increasing my workload in the lab... To its credit,dCS is, I believe, unique in curating digital filters whose coefficients (and hence
the transition band, stopband, response and ringing characteristics) are adapted
to each sample rate in turn. So, while Filters 1-4 and 6 are all linear phase types
their performance with 44.1/48kHz media changes with 96kHz or 192kHz files.
The permutations are considerable, if you have the time, patience andauditory acuity to explore them all! For example, Filter 1 [black trace, insetGraph], Filter 2 [red] and Filters 3 [cyan] and 4 [orange] retain a ruler-flat
response (–0.02dB/20kHz) with 44.1/48kHz media but trade progressively
poorer stopband rejection (108dB for Filter 1 to just 16.6dB for Filter 4) forreduced pre/post-ringing. With 192kHz files these same four filters have very
different HF responses – a steep cut to –13dB/90kHz, Filter 1; a gentler roll-offto –7dB/90kHz, Filter 2; an early post-20kHz roll-off to –6dB/56kHz, Filter 3; anda gentler post-30kHz roll-off to –18dB/90kHz, Filter 4. Filter 5 [green trace] isa minimum phase type with low sample rates but a NOS/Gaussian type above
176.4kHz [hence the early –6dB/39kHz rollout with 192kHz media on the inset
Graph]. Filter 6 [purple] is another linear phase filter, but with a very long tap
length, trading extended ringing for exceptional stopband rejection. PMABOVE: Rotary and array of buttons will
navigate the various settings but the dCS app
will be more convenient for most usersof its digital inputs as well as runningit network connected and as a Roonendpoint, it’s impressive just how
consistent the Bartók APEX sounds. Thatsaid, a bugbear for me is the limitation ofits capability with DSD files. Yes, the Bartók
APEX now handles DSD128 with ease, butthe world has moved on somewhat, andmany of the files I am downloading thesedays are in DSD256 – not because I’m
playing the numbers game, but because
that’s how they were created. Yes, it’s
possible to play them by using Roon totake them down to DSD64 or DSD128– the software will recognise that’s theupper limit of the DAC’s capabilities – butmany DACs will now
handle these files intheir native form.
Rant over, andthat limitation
aside, the Bartók
APEX is a remarkably
accomplisheddevice. Its streaming
capabilities work
simply and cleanly,with no gremlins
encountered whether
with the Mosaic Control app or third-party
software running on a tablet or phone. And
the sound is both weighty and substantial,with excellent bass definition, while at thesame time fluid and superbly detailed.
Play an album like Brad Mehldau’s Your
Mother Should Know set of Beatles covers– and, curiously, one Bowie composition[Nonesuch 075597907407] – and thesound is all about realistic piano scale
and the illusion of the instrument being
played in the room before the listener.
It boogied through ‘I Saw Her Standing
There’, was limpid and soulful on ‘Here,
There And Everywhere’, and simply magicalon the album closer ‘Life On Mars?’. Indeed
whatever you play through the new Bartók,and however you choose to play it, you’re

www.hifinews.co.uk | Reprinted from Hi-Fi News for global distribution

LabreportdCS BartÓk APEXABOVE: Digital inputs span S/PDIF (two coax, one opt), two AES/EBU (on XLRs), one
USB-A for external HDDs, one USB-B for computer connection and a network port (onRJ45) – joined by clock I/Os (on BNCs) and variable analogue outs (RCA and XLR)

dragged closer to the performanceand immersed in the music.
With Father John Misty’s live
Off-Key In Hamburg [self-released,Bandcamp download], dCS’s DAC
slammed through ‘Hollywood
Forever Cemetery Sings’ with finedrive and presence – as was the casewith the whole album’s dense mix,including both a full band and theNeue Philharmonie Frankfurt strings– plus excellent clarity in the deliveryof the singer’s voice.

Rockin' and rollin'
The same goes for Yo La Tengo’s
almost improvisational recent
album This Stupid
World [Matador
OLE 1929CD],
recorded as live by
the American indie
rockers and produced
for maximum
immediacy; here theclean sound of thedCS Bartók DAC drove the grooveof the opening track, ‘Sinatra Drive
Breakdown’, underpinned by James
McNew’s rumbling bass and Georgia
Hubley’s tight drumming.
Even with the echo-overlaid
Stones track ‘It’s All Over Now’, from
12X5 [ABKCO/London Records 844
461-2], the Bartók APEX laid barethe simple nature of the recording,revealing the performance ofeach of the five with an appealingrawness that goes all the way
through to the all-too-short cover of‘Susie Q’ at the end of the set.
The way this reborn DAC digs
into the depths of a performanceand a mix serves well Jacob Shea’s
atmospheric, dramatic ‘The Arctic
Suite’, the centrepiece of violinist
Eldbjørg Hemsing and the Arctic
Philharmonic’s Arctic [Sony Classical
G010004635026E; 96kHz/24-bit
download]. The shimmering
simplicity of the solo instrument
was wonderfully delivered, as
was the weight and power ofthe full ensemble when required.
This persuasive balance carries
through to the intimacy of Brahms’‘Variations And Fugue On A ThemeOf Handel’, from Seong-Jin Cho’s
The Handel Project recital [DeutscheGrammophon 486 3018], wherethe focused view of the pianist’s
Steinway had both delicacy andspeed, as well as excellent solidity inthe lower octaves.

Fertile groundIf I submit the opinion that thesound of this DAC is precise, I don’tmean to suggest that it’s in any way
mechanical or sterile... Far fromit, as illustrated by Jessie Buckley’s
soulful reading of ‘Maybe This Time’from the 2021 London cast albumof Kander & Ebb’s Cabaret [Decca4873046]. It’s along way from theall-guns-blazing
Liza Minelli movieversion, but all
the better for
that, while Eddie
Redmayne’s MCis wonderfully
lascivious and sleazy, and equallywell served by a recording theBartók APEX revealed to be perfectly
set in its small-club location.
Add in that the sound was justas convincing with some highly
atmospheric radio dramas – yes, inglorious 320kbps AAC! – and it’s
clear this latest arrival from dCS is
not only a remarkable DAC, but also
now firmly in that rarefied group of
top-notch network players.

Supplied here minus its headphone amplifier [HFN May ’19]
but enjoying the fruits of dCS’s APEX upgrade to the Ring DACarray we saw launched in the flagship Vivaldi [HFN Jun ’22],
the Bartók now has an enhanced purpose as the brand’s ‘entry
level’ full-width digital source. While the various upsampling/
format conversion and digital filter options [see boxout, p49]
remain unchanged, the performance advantages offered bythis APEX version of the Bartók are easily ‘measurable’. While
the peak/0dBFs output remains at 5.89V (balanced), the output
impedance is fractionally lower (from 0.7ohm to 0.5ohm) andthe A-wtd S/N ratio wider (from 116.6dB to 117.5dB). Similarly,
while distortion at peak output remains stupendously low at just
0.00005-0.00025% (20Hz-20kHz) the APEX upgrade sees thisreduced still further over the top 30dB of the Bartók’s dynamicrange [see Graph 1, below] from 0.0001-0.0004% (Bartók) to
0.00003-0.0001% (Bartók APEX) at –10dBFs (20Hz-20kHz) andfrom 0.0002-0.0006% to 0.0001-0.0002% (–30dBFs, 20Hz20kHz), respectively. Jitter, too, falls from 10psec to ~7psec inthis APEX variant. Granted, these are very small numbers, butthey are still clearly illustrative of positive, incremental change at
the cutting edge of the state-of-the-art.
The impact of dCS’s LPCM-to-DXD and DSD upsampling isshown in Graph 2, where the increase in ultrasonic requantisationnoise, and correlated 2nd/3rd harmonic distortions (with a20kHz/0dBFs signal), to DSD128 [green] and DSD64 [black]compared to DXD [red] is very clear. Five DSD filters are offered,
Filter 1 offering a steep –6dB/83kHz rollout after upsamplingfrom 192kHz LPCM, with Filters 2-5 reaching 76kHz, 70kHz,
33kHz and 39kHz (all –6dB re. 1kHz), respectively. PM‘It’s simply
magical on thealbum closer“Life On Mars?”’

ABOVE: Distortion vs. 24-bit digital signal level over a
120dB range at 1kHz (black) and 20kHz (blue)

HI-FI NEWS VERDICTYes, it’s quite a leap in price fromthe original Bartók to this new
APEX version, but the gains inperformance are more thancommensurate with the uptick.
This may be the ‘entry-level’ dCSoffering, but there’s no hint ofthat in a sound as revealing as it isinvolving, with excellent scale andresolution. Factor in the flexibility,
its solidity of build and the clarityof its control app, and this is avery superior unit.

Sound Quality: 88%
0-------- 100

ABOVE: 20kHz/0dBFs at 192kHz/24-bit upsampled to
DSD (black), DSDx2 (green) and DXD (red)HI-FI NEWS SPECIFICATIONS
Maximum output level / Impedance

5.89Vrms / 0.5ohm

A-wtd S/N ratio (USB / Network)

117.5dB / 117.5dB

Distortion (1kHz, 0dBFs/–30dBFs)

0.00005% / 0.00009%

Distortion & Noise (20kHz, 0dBFs/–30dBFs)

0.00025% / 0.00025%

Freq. resp. (20Hz-20kHz/45kHz/90kHz)+0.0 to –0.0dB/–0.6dB/–7.1dB

Digital jitter (48kHz / 96kHz)

7psec / 8psec

Resolution (re. –100dBFs / –110dBFs)±0.2dB / ±0.4dB

Power consumption

22W (21W standby)

Dimensions (WHD) / Weight

444x115x430mm / 16.7kg

www.hifinews.co.uk | Reprinted from Hi-Fi News for global distribution