have actually changed little in the last 30 years. For sure, fidelity and
linearity have improved, but the operation remains essentially the same. They
still convert digital audio into analogue, and the core requirement is still
focused on CD's 16-bit/44.1kHz PCM standard. Around 20 years ago the bit-depth
and sample frequency capability of the best DACs increased to 24-bit/96kHz,
aligning with the first high resolution digital audio recordings. But even after
the launch of SACD's competing 1-bit DSD format, external consumer hi-fi DACs
remained firmly in the familiar PCM world, thanks to Sony and Philips' success
in excluding general access to the unencrypted DSD datastream. Only after SACD
had effectively become obsolescent was 1-bit PDM digital put to good use in
external DACs. The result today is that many consumer DACs made in the last five
years now have bilingual fluency in both PCM and DSD formats.
adds a third option. It's the first independent DAC to market that
can handle a brand-new higher definition digital datastream devised by Meridian
Audio, known as Master Quality Authenticated (MQA). Economical in information
density for downloading and storage, it essentially promises the sound quality
of 24/96. (see Colloms on MQA, HIFICRITIC
The Brooklyn comes
similarly packaged in a half-width compact box, 1U in height, one of several
clues to its pro-audio background. Changes include the latest converter chips,
an ESS Sabre 9018K2M replacing the
which sees a specified THD+N figure lowered from -110 to -120dB; this chip uses
a proprietary 32-bit Hyperstream architecture which excels at DSD as well as PCM
conversion, using a cascade of independent sigma-delta modulators with
adjustable bit-width output (typically 6-bit).
The USB front end has been updated by a Class 2
USB 2.0 digital receiver. Windows users will still need to install dedicated
drivers, but Linux and OS X computers now require no additions for operation up
to a 384 kHz sampling capability. (A welcome situation since Mytek's development
of the custom OS X driver for the Stereo192-DSD
was abandoned last year, effectively marooning that product for Mac
Gone, however, is the FireWire input, which
proved the best-sounding option on the Stereo192-DSD.
Mytek founder Michał Jurewicz agrees that FireWire is better
suited to audio, but TC Technology discontinued the required DICE
Mini 1394 receiver, leaving Mytek to focus on the USB input. While
not fully galvanically isolated, ground planes are separated to reduced
conducted noise. Traditional digital inputs comprise two S/PDIFs
A stylish honeycomb pattern is etched into the
surface of the front fascia, and the unit is available in silver or black
finish. Two 0.25in headphone outputs can either power two pairs of headphones,
or be combined to give balanced-mode drive for suitable 'phones via
a double-jack-plug-to-XLR adapter.
A contentious revision may be the replacement of
the internal linear supply by a switch-mode power supply. This provides the
advantages of international voltage compatibility, reduced cost and higher
efficiency, although audiophiles are rightly wary of such devices.
Notwithstanding the module's perforated Faraday cage screening, these supplies
are known to affect sensitive audio circuitry through radio-frequency switching
noise. (Mytek has thoughtfully added an external power inlet on the rear panel,
letting one use an external 12V linear supply instead.) While Mytek doesn't make
such a unit itself, specialist suppliers have already accepted the challenge:
Longdog Audio makes just such a power supply (£495, or £425 if bought with the
DAC). This linear supply was tried on the Brooklyn,
with beneficial results. Remote control is still possible via a supplied Apple IR handset.
The Brooklyn has
a new multi-colour OLED display which provides detailed feedback on operations.
The basic five-element peak level meters of the Stereo192-DSD
are expanded to a 37-level bar graphic with numerical peak and
average readings, that can help identify which recordings have been subject to
loudness-war compression. Two alternative display modes include a simple screen
showing volume setting, bit depth and sample frequency; and the full setup with
adjustable parameters and the aforementioned meters. While the more intricate
display is a marvel to navigate, its small fonts can now only be used up close,
rather than viewed and adjusted from across the room. Ongoing firmware upgrades
during the review period have already expanded the Brooklyn's feature set, adding absolute polarity and new
mono modes; expect more improvements in future. Build quality remains excellent,
though I did miss the precise action of the outgoing Stereo192-DSD's
control knob, as the Brooklyn's
knob has more play and less precise click detents.
MQA was officially launched in December 2014.
Rather more than just a digital codec, it's a complete end-to-end ecosystem for
the distribution and playback of higher-resolution digital audio. Its inventors
would rather dwell less on the digital technologies it employs as on the
complete analogue-to-analogue signal chain from studio microphone to domestic
amplifier (which just happens to include digital encoding, mostly lossless
compression, digital distribution and then digital decoding along the way).
At its core MQA is still modeled on pulse-code modulation (PCM), but with surprising twists. An unpacked music file is specified in PCM terms of bit depth and sample frequency, typically sized as 24-bit/96kHz or 24/192; or based on CD baseband frequencies (hence 24/88.2, 24/176.4 and 24/352.8). Yet these hi-res recordings are packed and distributed in smaller packages that are recognised by legacy converters as either 24/48 or 24/44.1 files, with commensurately modest files sizes and streaming bitrates.
The Brooklyn accepts
the still-packed datastream from a Mac or Windows PC over USB, then unfolds the
buried data in a technique that creator Bob Stuart calls 'audio origami'.
Interleaved throughout the digital data, a retrievable and reversible watermark
is locked down by strong cryptography that requires embedded hardware keys to
unlock, so only licensed decoder modules can access the full high-resolution
content. The watermark includes song metadata, copyright and licensing
information, and instructions on the required unwrapping and filter strategy for
an MQA DAC. The listener needs only to know that a green 'authenticated' light
shines. (An alternative blue light indicates that the encode is 'MQA Studio',
meaning that the final rendition was signed-off by the original artist or
MQA also addresses an aspect of PCM technology
that still troubles much of today's digital audio sampling – the meddling of
both anti-alias and reconstruction filters. These typically introduce phase
errors or ripples in impulse response (especially so in traditional 'brickwall'
filters). MQA performs 'deblurring': erasing the fingerprint of the filters by
using selected encode and decode filters which when combined produce more
compact impulse response particularly in terms of the more troubling pre-ringing,
which some contend relates to the hardening of piano timbres.
'black-box' MQA module resides in an XMOS microcontroller on the main circuit
board and can be enabled or disabled through the display interface. Three
digital reconstruction filters are offered for general PCM playback – FR, SR
and MPH. These signify fast and slow roll-off linear-phase FIR filters for
general PCM, while the final minimum-phase filter is mandated for MQA playback.
My initial concern about the downgrade from
FireWire to USB connection proved largely unfounded. Although the Stereo192-DSD-through-FireWire
always sounded well-timed with precise, steady imaging, recourse to USB would
somewhat Brooklyn's new crystal
clock (named Femtoclock, but not
from the IDT company which originated the name), or the updated UAC 2 USB
receiver, I found that the new DAC provided the same level of structural
solidity and focus, but that picture-painting detail was clearly improved
Set against the far-from-opaque Stereo192-DSD, the Brooklyn managed to uncover rather more of the low-level detail that can draw one into a recording. This isn't highlighted detail from an upward tonal shift, so much as a wiping of the merest trace of mist from spectacle lenses. Returning to the Stereo192-DSD after trials of the Brooklyn, I found myself metaphorically leaning towards the speakers to catch what now seemed like missing musical detail.
The stock Brooklyn
has a relatively dry sound, with a fractionally leaner and more even
bass than its predecessor, but revelatory voicing brings the soundstage slightly
closer. It does therefore miss out on the rounded and engaging bass quality that
makes the Stereo192-DSD's bass lines more playful, revealing instead
a faintly sterile attitude to the low notes. The top end sounds essentially
sweet and vice-free, yet there is also some room for improvement, as I found
when using an external power supply.
The external MCRU/Longdog linear supply enhanced
timbral colour and wiped away some residual grain from an already clean-sounding
DAC, and demonstrated clearer instrument separation. Initially I had
reservations about speed and timing, as bass pace seemed to be slowed
perceptibly, but this was remedied in turn by using an unfiltered mains
connection rather than an Isotek Titan conditioner. Best performance was finally established
by routing all the powered components through a Puritan PSM136
mains purifier, and now the Brooklyn
fed by a linear PSU was in super-fi territory.
The balanced-mode headphone drive was a bonus.
Using the adapter-plus-balanced-cable on Oppo PM-1
headphones gave palpably more grip and control, and improved dynamics
created a more engaging sound. The limited selection of 20 tracks provided by
MQA showed substantially lifelike transient details, as witnessed for example on
the cymbal work of jazz piece Dark Dance by
the Tomonao Hara Quartet.
However, the comparison could only be made
between legacy playback (MQA disabled) for a 16/48-like version, and the full
24/192 unpacked file. Classical piano could sound outstanding from MQA material.
A Chopin Prelude in B Minor was tripped of some honky-tonk clanginess that was
evident in legacy mode, to reveal sonorous hearthrough notes decaying into a
medium-sized room's clean acoustic space. The cherry-picked demo selection
augers well for how MQA-treated hi-res recordings can sound, in the traditional
audiophile sense. But some mainstream favourites will also be required in order
to understand how well, for example, familiar rock, pop and jazz music times.
Playing with the three available PCM filter
settings while switching between normal PCM and MQA tracks did however uncover a
strong personal preference for the SR 'slow' filter on regular recordings. The
minimum-phase filter could bring more clarity and precision to instrumental
strands, tightening attack with cleaner incisiveness; this might all sound fine
in quick-fire tests, but it also seemed to remove some of the sense of the
musical flow. Rather like watching a movie where the audio leads the video by
more than 50ms, it's still quite possible to watch and enjoy the film, but the
slipped lipsync ultimately becomes wearing as the eye, ear and brain work to
mesh the whole coherently within the head.
Set to MPH, top-to-bottom timing suffered, so
recordings simply became less captivating. I found myself 'tuning out' music
after a while as my attention wandered. The SR slow roll-off filter on the other
hand gave the most relaxed sound for long-term listening prospects,
front-to-back stereo imaging laid out in a more emphatic manner. And despite the
potential for stop-band artefacts drifting down into the passband, I couldn't
find any music that would introduce any distracting 'fizz' to the sound.