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TEST Bluetooth DAC

wealth of app sources. And the sound! If this really was SBC (we suspect it may have been 256k AAC), we’re amazed. Even in a revealing system the sound had none of the common flaky edges we’ve heard from low-fi Bluetooth transmission. We might switch to the direct USB input for critical evening listening (retaining iPad control using the ‘Remote’ app to control iTunes), but otherwise this really was Bluetooth convenience turned into hi-fi. Such quality could make Bluetooth more useful system than, say, AirPlay, certainly in terms of broad compatibility.

How has Musical Fidelity managed this? The company does make much of how it treats the Bluetooth input as not merely a bolted-on extra. The received data is fed into its upsampling DAC like any other input, so perhaps that’s the secret.

Back on the asynchronous USB input, we enjoyed the M6DAC’s performance at its best, loading the 24-96 file of ‘Here Lies Love’ from Diana Krall’s Gladrag Doll and enjoying pure studio master sound (ground-level analogue tape hiss included!). One minute in, the band entry was a truly weighty moment, the Waitsian guitar work from Marc Ribot positively delicious in a spacious and distant acoustic of its own off in the right channel, and when Krall thumped through her bar-room piano solo in the midst of it all, you could just see those hammers rise and fall.

We had the pleasure of having both the M6DAC and the NAD M51 (see p74-75) in parallel connection at the same time — this made for a complicated A-B but one that nevertheless revealed a clear difference between their characters. The M6 yielded music that was notably warmer in tone, while the NAD offered an apparently sharper-edged clarity, like you could see through the gaps between the lines.

It might be easy to think the M6’s warmth more musical, and the NAD M51’s sharp edges more clinical. But the NAD had no trouble delivering the feel of the music, while the Musical Fidelity’s warmth by no means equated to softness. Indeed when we played a recent 24/96 acquisition — Monk, a NYC Tribute, featuring Jimmy Cobb and Randy Brecker — this unusually close-miked affair was delivered with devasting impact through

Musical Fidelity has been making high-end DACs since its Digilog back in the barely-digital year of 1987, when upgrading early

CD players was all the rage. Today’s DACs need to handle digital outputs from multiple sources, including direct links from computer via USB. So the M6DAC brings the company’s considerable experience to bear on a high-level hi-fi component DAC which not only fulfils the usual functions and connections, it adds the unusual (at this level) bonus of Bluetooth streaming. Yes, you heard us right, Bluetooth — so you can pair an iPhone, iPad or Android device with it and zap your music across. It’s all very populist for a high-end DAC — so what’s going on?

EQUIPMENTThe DAC type used within the M6DAC is a 24-bit Delta-Sigma device, which uses dual differential 8× over-sampling, asynchronous

BLUETOOTH SURPRISEMusical Fidelity has added Bluetooth to its statement high-end DAC. It sounds great, though we’re not entirely sure why.

connection via USB, and upsampling on all inputs to 192kHz. You can toy with the output filter via remote control to switch between a fast roll-off (to -3dB at 0.49× the sampling frequency) or a slow roll-off (to -3dB at 0.45× the sampling frequency). The inputs to the DAC section include one AES balanced type via XLR socket, two coaxial digital and one optical digital inputs, and the asynchronous USB-B socket to receive from your computer. The company describes this last as “a slightly improved version of the V-Link 192”, the USB-to-SPDIF converter that regular readers may remember from a previous review.

Then there’s that Bluetooth receiver, for which a small antenna is provided on a cable long enough to get the antenna somewhere useful even if the M6DAC is in a cabinet.

Line-level outputs are available as balanced XLRs or standard RCA phono sockets, and the M6 also does the courtesy of providing digital outputs as electrical or optical digital, or again as balanced AES via XLR.

If you’re in the habit of switching between digital inputs on a preamp, you may have noticed that there can be quite drastic level differences between sources especially if you’re using any volume control on your computer (which you shouldn’t, ideally). The remote control for the M6 allows you to set input levels for each input, despite their digital nature, so that matching across your componentry is

easy, a small thing that might save your ears, even speakers, from sudden alarm. You can also name inputs as you wish.

PERFORMANCESo let’s start with that Bluetooth. It’s no small thing, this, in convenience terms (unless you have managed to get this far in life without acquiring a smartphone, tablet or laptop). By pairing your device with the Musical Fidelity you can send audio from pretty much any app or program straight to your hi-fi. Flicking tunes to a high-end hi-fi while browsing internet radio or your iTunes music collection on a tablet is an experience to be savoured.

But what of the quality of Bluetooth? It’s no secret that the standard version of Bluetooth (A2DP using the Sub-Band Codec, SBC) isn’t hi-fi quality music streaming — judging by

INPUTS: XLR AES balanced digital; coaxial digital; optical digital; USB-BBLUETOOTH: v2.1+EDR profile, SBC and aptX codecs OUTPUTS: Line-level RCA analogue; line-level XLR analogue (balanced); optical, coaxial and AES digitalCONTROL: 12V trigger in/outQUOTED JITTER: <12 picoseconds peak to peakDIMENSIONS (whd): 440 x 102 x 380mmWEIGHT: 10.6kgWARRANTY: Two years

CONTACT: Audio MarketingTEL: 02 9882 3877WEB: www.audiomarketing.com.au

• Excellent conversion • Musical sound• Inexplicably good Bluetooth

performance

• Bigger, pricier than some

VERDICT

Musical Fidelity M6DACdigital-to-analogueconverterPrice: $3495

bit-rate alone it’s more MP3 than CD. Well, the M6DAC supports a superior codec as well — aptX. The apt-X codec delivers 16-bit 44.1kHz music, the same as CD, though the bit-rate indicates there’s some compression used to achieve it. Implemention of aptX on smartphones is growing (it’s on the new Galaxy S4) but it’s still only on a minority of devices, and isn’t currently supported by any Apple products (aptX’s owners CSR have a list of products supporting the codec but it’s not easy to find; shortcut: bit.ly/WznXvz).

Owners of Apple devices a few generations back might hope that they could fall back on V2.1+EDR, since the EDR part (Enhanced Data Rate) can achieve a theoretical 3Mbps and a practical 2.1Mbps — this is why Apple is so enamoured of V2.1+EDR and insists on its implementation in all Apple Bluetooth accessories, including non-audio devices. Such speeds should allow higher than CD quality, and higher than apt-X. Yet you’ll find no one claiming to achieve this. Why not?

In our discussions with the engineers at Musical Fidelity (see EdLines comment p8), it emerged that while two devices with EDR can communicate at faster-than-CD bit-rate speeds, there is no Bluetooth codec available to take advantage of the speed. So this was disappointing news, as it meant the apparent match in profiles between our iPad 2 and the M6DAC (both Bluetooth profile V2.1+EDR) counts for nothing — without aptX, the connection would fall back to the grungy old SBC Bluetooth codec.

As a further complication, newer devices have moved to Bluetooth v4.0, a low-power Bluetooth which saves energy but cuts the available transmission bit-rate. It can’t match EDR, and looks on paper as if apt-X’s 352kbps bandwidth might challenge V4.0’s application throughput rate. But since there are plenty of V4.0 phones around offering apt-X, we assume there’s a workaround. One thing’s for sure, it’s still early days for knowing how to get the best from Bluetooth in a hi-fi context.

One thing was certain, however — the Musical Fidelity sounded pretty wonderful when streaming from our iPad 2. Pairing was simply a case of selecting the MF’s Bluetooth input and finding it in the iPad’s ‘Settings’ app — presto, welcome to handheld control and a

Musical Fidelity M6DACdigital-to-analogue converter with BluetoothPrice: $3495

the M6DAC, the dynamics huge, the imaging razor sharp yet entirely unfatiguing, for a thrilling experience and an excellent demon-stration of the M6 DAC’s ability to deliver precision and solidity within a rich natural sound — one of our listening notes says “like vinyl, but faster”. It delivered near-square-edged percussive elements as real transients pin-pricked across the soundstage. The poten-tially edgy trumpet lines were edgy like the real thing, not edgy through reproductive failure.

CONCLUSIONThe M6 illuminates it all. It’s a window to the wonderful world of music. We don’t understand how the Bluetooth input sounds so good, but we can’t deny it does, while the more conventional digital inputs have all the high-end attention to detail that ensures spectacular clarity whatever the bit-rate. This is new-age hi-fi at its best. Jez Ford