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<p><img class="story_image" src="http://www.stereophile.com/images/613mdac.promo_.jpg" /></p>
For the past few years, one of <i>Stereophile</i>'s go-to recommendations for affordable high-performance D/A processors has been the M1DAC from British company Musical Fidelity. The M1DAC was enthusiastically reviewed by Sam Tellig in March 2011, and I wrote about the most recent version in <a href="http://www.stereophile.com/content/musical-fidelity-m1-dac-john-atkinson-january-2013">January 2013</a>. "Purity of tone was exceptional," decided Mr. T., which I found to be accompanied by superb measured performance, all at a very reasonable price: $749.
<p>
So when I learned, at the <a href="http://www.stereophile.com/content/musical-fidelity-m6-series-reference-dac">2013 Consumer Electronics Show</a>, of Musical Fidelity's new M6DAC, intended to offer "reference quality" performance at a relatively affordable price ($2999), I asked for a review sample.
</p><p>
<b>The M6DAC</b><br />Housed in a black-painted steel enclosure, with ribbed aluminum side panels and a black or silver aluminum front panel, the M6DAC matches the styling of Musical Fidelity's other M6-series amplifiers and CD player. A rectangular, blue-illuminated LCD display dominates the left-hand side of the front panel, showing the source playing, the sample rate, and whether that source is set for a fixed output level or adjustable level. A rear-panel switch allows the M6DAC's output level for each input to be set to fixed or, within a range of ±10dB, independently adjusted with Up and Down buttons on the front panel and remote control.
</p><p>
The M6DAC offers a choice of two reconstruction filters, labeled Fast Roll Off and Slow Roll Off, selectable with a front-panel Filter button duplicated on the remote. The display momentarily shows which filter has been selected, as well as whether de-emphasis has been set to Auto or Off. As well as the buttons mentioned above, the array of 10 pushbuttons on the right-hand side of the front panel allows six different sources of data to be selected: balanced AES/EBU on an XLR jack, two S/PDIF electrical inputs on RCA jacks, S/PDIF optical on a TosLink jack, asynchronous USB on the usual USB Type B jack, and Bluetooth.
</p><p>
<img src="http://www.stereophile.com/images/613mdac.bac.jpg" alt="613mdac.bac.jpg" width="600" height="285" border="0" /></p><p>
On the rear panel, a badge proclaims that though the M6DAC is made in Taiwan, it was designed in England. On the central section are a pair of RCA jacks for the single-ended analog output, and a pair of XLRs for the balanced analog output. To the right of these are the IEC AC jack and trigger in and out jacks; to the left are the digital inputs, as well as a screw connector for the supplied Bluetooth antenna and three digital outputs: AES/EBU on XLR, S/PDIF optical on TosLink, and S/PDIF electrical on RCA. The Bluetooth connection needs to be set up with a paired device in the usual way, entering a code on the device when instructed. The USB2.0 port functions without a driver program with Linux 2.6.33 or later and Mac OSX 10.6.4 or later. The drivers needed for Windows XP (SP3), Vista, and 7 are included on a CD-ROM. The manual doesn't mention Windows 8, but does include a comprehensive section on getting the optimal performance from Windows machines.
</p><p>
The plastic remote includes buttons for operating both the M6DAC and the M6CD player. Two of its buttons are not duplicated on the front panel: Mute and Display, the latter offering two levels of illumination as well as Off.
</p><p>
<b>Circuitry</b><br />When I lifted off the M6DAC's steel top panel, I saw an interior dominated by a large, double-layer, green printed circuit board, with a cutout at the front center to accommodate the AC transformer. This transformer is flanked by blue 4.7µF polypropylene capacitors: 18 on one side, 14 on the other. Almost all the circuitry is concealed by two black metal covers, the one on the left marked "Universal Precision Regulated Digital Power Supply" and offering choke smoothing, the one in the center marked "Fully Balanced Precision Dual Mono 192kHz 24 bit Upsampling Quad DAC." Only the digital-input receiver components are out in the open, with a Bluetooth LSI on the main board and the XMOS USB receiver mounted on a small daughterboard behind the digital input jacks. All digital inputs are galvanically isolated, to minimize noise being injected into the circuit ground.
</p><p>
<img src="http://www.stereophile.com/images/613mdac.ins.jpg" alt="613mdac.ins.jpg" width="600" height="362" border="0" /></p><p>
Removing the shield from the signal-handling stages revealed that the i<sup>2</sup>S data from the digital inputs are fed to a Burr-Brown SRC4392 chip, an asynchronous sample-rate converter found in many of Musical Fidelity's digital products. Whatever the incoming sample rate, this chip upsamples it to 192kHz and feeds left- and right-channel 24-bit data to a pair of Burr-Brown DSD1796 DAC chips, one per channel. This DAC is a two-channel part; Musical Fidelity uses the two channels in differential mode to provide a balanced mono signal path, with each channel's circuit physically separate from the other's. I/V conversion appears to be performed by a Texas Instruments LME49720 dual
[Source: http://www.stereophile.com/content/musical-fidelity-m6dac-da-processor]
For the past few years, one of <i>Stereophile</i>'s go-to recommendations for affordable high-performance D/A processors has been the M1DAC from British company Musical Fidelity. The M1DAC was enthusiastically reviewed by Sam Tellig in March 2011, and I wrote about the most recent version in <a href="http://www.stereophile.com/content/musical-fidelity-m1-dac-john-atkinson-january-2013">January 2013</a>. "Purity of tone was exceptional," decided Mr. T., which I found to be accompanied by superb measured performance, all at a very reasonable price: $749.
<p>
So when I learned, at the <a href="http://www.stereophile.com/content/musical-fidelity-m6-series-reference-dac">2013 Consumer Electronics Show</a>, of Musical Fidelity's new M6DAC, intended to offer "reference quality" performance at a relatively affordable price ($2999), I asked for a review sample.
</p><p>
<b>The M6DAC</b><br />Housed in a black-painted steel enclosure, with ribbed aluminum side panels and a black or silver aluminum front panel, the M6DAC matches the styling of Musical Fidelity's other M6-series amplifiers and CD player. A rectangular, blue-illuminated LCD display dominates the left-hand side of the front panel, showing the source playing, the sample rate, and whether that source is set for a fixed output level or adjustable level. A rear-panel switch allows the M6DAC's output level for each input to be set to fixed or, within a range of ±10dB, independently adjusted with Up and Down buttons on the front panel and remote control.
</p><p>
The M6DAC offers a choice of two reconstruction filters, labeled Fast Roll Off and Slow Roll Off, selectable with a front-panel Filter button duplicated on the remote. The display momentarily shows which filter has been selected, as well as whether de-emphasis has been set to Auto or Off. As well as the buttons mentioned above, the array of 10 pushbuttons on the right-hand side of the front panel allows six different sources of data to be selected: balanced AES/EBU on an XLR jack, two S/PDIF electrical inputs on RCA jacks, S/PDIF optical on a TosLink jack, asynchronous USB on the usual USB Type B jack, and Bluetooth.
</p><p>
<img src="http://www.stereophile.com/images/613mdac.bac.jpg" alt="613mdac.bac.jpg" width="600" height="285" border="0" /></p><p>
On the rear panel, a badge proclaims that though the M6DAC is made in Taiwan, it was designed in England. On the central section are a pair of RCA jacks for the single-ended analog output, and a pair of XLRs for the balanced analog output. To the right of these are the IEC AC jack and trigger in and out jacks; to the left are the digital inputs, as well as a screw connector for the supplied Bluetooth antenna and three digital outputs: AES/EBU on XLR, S/PDIF optical on TosLink, and S/PDIF electrical on RCA. The Bluetooth connection needs to be set up with a paired device in the usual way, entering a code on the device when instructed. The USB2.0 port functions without a driver program with Linux 2.6.33 or later and Mac OSX 10.6.4 or later. The drivers needed for Windows XP (SP3), Vista, and 7 are included on a CD-ROM. The manual doesn't mention Windows 8, but does include a comprehensive section on getting the optimal performance from Windows machines.
</p><p>
The plastic remote includes buttons for operating both the M6DAC and the M6CD player. Two of its buttons are not duplicated on the front panel: Mute and Display, the latter offering two levels of illumination as well as Off.
</p><p>
<b>Circuitry</b><br />When I lifted off the M6DAC's steel top panel, I saw an interior dominated by a large, double-layer, green printed circuit board, with a cutout at the front center to accommodate the AC transformer. This transformer is flanked by blue 4.7µF polypropylene capacitors: 18 on one side, 14 on the other. Almost all the circuitry is concealed by two black metal covers, the one on the left marked "Universal Precision Regulated Digital Power Supply" and offering choke smoothing, the one in the center marked "Fully Balanced Precision Dual Mono 192kHz 24 bit Upsampling Quad DAC." Only the digital-input receiver components are out in the open, with a Bluetooth LSI on the main board and the XMOS USB receiver mounted on a small daughterboard behind the digital input jacks. All digital inputs are galvanically isolated, to minimize noise being injected into the circuit ground.
</p><p>
<img src="http://www.stereophile.com/images/613mdac.ins.jpg" alt="613mdac.ins.jpg" width="600" height="362" border="0" /></p><p>
Removing the shield from the signal-handling stages revealed that the i<sup>2</sup>S data from the digital inputs are fed to a Burr-Brown SRC4392 chip, an asynchronous sample-rate converter found in many of Musical Fidelity's digital products. Whatever the incoming sample rate, this chip upsamples it to 192kHz and feeds left- and right-channel 24-bit data to a pair of Burr-Brown DSD1796 DAC chips, one per channel. This DAC is a two-channel part; Musical Fidelity uses the two channels in differential mode to provide a balanced mono signal path, with each channel's circuit physically separate from the other's. I/V conversion appears to be performed by a Texas Instruments LME49720 dual
[Source: http://www.stereophile.com/content/musical-fidelity-m6dac-da-processor]