Vinnie Rossi L2 Signature Preamplifier (Part 3—The DAC Module)

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Before reading this post, please check back to the full review of the Vinnie Rossi L2 Signature Preamplifier. It’ll give you a better understanding of this DAC module review. It may be fun to read the Phono Stage module review, too. It’s the other plugin available for this fully functional and brilliant preamplifier.

The Phono and DAC modules’ MSRP is $3495 each. They are both plug and play. Unscrew the four screws, remove the plate, install the module. Click, rescrew, done.

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My Use

The DAC module has three inputs, Optical, Coaxial and USB, my favoured input. I used an Audioquest Carbon USB cable between my Antipodes Audio CORE Music Server and the module. The beauty of the module is fewer interconnects and power cords to purchase. I wrote about the smaller audiophile footprint in the Phono module review. The same for the DAC. One has to be careful with downsizing; in contrast to Hollywood’s mantra, you can be too skinny.

I recently reviewed the $5995 Mytek Manhattan DAC II with its onboard network streaming card option ($1495). I thought my digital problems were over. But, no. The DAC was brilliant, the card less so. The digital files sang more beautifully through the Antipodes server and its onboard Roon Core. My other recent DAC review was the T+A Elektroakustik DAC 8 DSD High End D/A Converter ($4450). No options attached to this splendid German box, just digital done right—smooth, detailed, refined, with filters aplenty and no fatigue.

These two DACs form the short, comparative list for this review. Granted, they are both non tube, standalone units (to which, I am usually attracted), and both are significantly more expensive. I do try to compare kit similarly priced, but that option was not available. After the excellent review the Vinnie Rossi Phono module received, I’m not sure the DAC module is that bothered. These modules box well above their weight.

The module plates located on the rear panel. Undo four screws for each of the two modules, plug and play.

The module plates located on the rear panel. Undo four screws for each of the two modules, plug and play.

L2 DAC Features

  • Bit-perfect playback at sampling rates up to PCM 768kHz (16, 24, or 32 bit compatible), as well up to DSD512. Sample rates are viewable from front panel display.

  • Dual-mono design, with one flagship AKM AK44497EQ d/a chip per channel.

  • Fully discrete, pure Class-A JFET analog outputs stage design with cascode constant-current source biasing (no opamps).

  • On-board FPGA buffer and femto-reclocking circuitry negates effects of jitter. Isolated input stages.

  • ‘NOS’ (non-oversampling) filter mode with digital filter bypass, as well as a Minimal Phase digital filter mode (selected via the “FILTER” button on the L2 Remote).

  • Absolute polarity ‘normal’ / Absolute polarity ‘inverted’ modes (selected via the “PHASE” button on the L2 Remote).

  • Belleson Super-regulated voltage feed to numerous ultra-low noise, linear voltage regulators used throughout (for both digital and analog sections).

  • “Silent” mute ‘reed relays’ (*barely* an audible click from the board when changing tracks of a different sample rate).

  • Inputs: 1 USB, 1 Coax (75-ohm BNC, with included RCA adapter) and 1 TOSLINK (optical).

  • Connect up to three devices and switch between them via L2 front panel or the remote handset.

L2 DAC Specifications 

  • Output Voltage: 2.0V rms

  • Output Impedance: < 100 ohms

  • SNR: > 115dB

  • Playback Bit Rates Accepted (PCM): 16, 24, 32

  • PCM Playback—Windows PC: 44.1, 48, 88.2, 96, 176, 192, 352, 384, 705, and 768kHz – driver included. Mac OSX: 44.1, 48, 88.2, 96, 176, 192, 352, 384, 705, and 768kHz – no driver required. Sonore: 44.1, 48, 88.2, 96, 176, 192, 352, 384, 705, and 768kHz

  • DSD Playback—Windows PC: DSD64, DSD128, DSD256, and DSD512 (both Native mode, and DoP) – driver included. Mac OSX: DSD64, DSD128, DSD256 (DoP) – no driver required. Sonore: DSD64, DSD128, DSD256, and DSD512 (both Native mode, and DoP)

Sound

Much like the Phono module, I allowed a week of casual listening for break-in. And once again, the unit shone as soon as it was heard. My ears became accustomed to the detail and refinement as the week wore on.

DAC specs can boggle the mind; not bullshit baffles brains, but Rossi provides a litany of numbers allowing the DAC to be fairly future proof. The module uses two AKM AK44497EQ chips, one per channel. Play ripped CDs, bog standard CDs, 192s from HD Tracks or higher bit rates, or stream Tidal Hifi and/or Qobuz HiRes files to your heart’s content. Unless you adhere to FPGA topology used by a couple of manufacturers (upgrades via firmware after manufacture), you’ll be very impressed by the technology within. Rossi’s parts list reads like a who’s who of advanced digital technology manufacturers.

So far, so good. Lots of goodies inside, but do they provide the best that digital music has to offer?

The Rossi module has only two filters…”NOS’ (non-oversampling) filter mode with digital filter bypass, as well as a Minimal Phase digital filter mode (selected via the “FILTER” button on the L2 Remote)”.

This brief filter list caught my attention considering the multitude of filters found on the Mytek and T+A boxes. I asked Rossi his thinking behind his choice:

The default filter is the non-oversampling, digital filter-less mode (my discrete, class A JFET analog output stage contains my own filter). This is what I believe sounds the most natural and what I recommend always using, but the minimal phase filter setting can also be tried. It internally upsamples all PCM to 768kHz and uses the AK4497 d/a chips' internal minimal phase digital filter with slow roll-off slope. It will measure better on the test bench in terms of lower noise outside the audio band, while still sounding enjoyable.

I decided on offering my two favorite sounding filter modes and ditching all the others (especially the linear phase digital filters, which having pre-ringing on their impulse response plots). The default nos mode is really the way to go [my filter of choice for the entire review period], and if you want to play with upsampling, I highly recommend staying with nos mode and doing the upsampling in Roon ("Sample Rate Conversion" settings) and converting everything to DSD256 or DSD512 via Roon. Roon does a fine job at this.

Using dual AKM AK4497 d/a chips (dual mono) for the L2 DAC was very appealing to me because of its non-oversampling, digital filter bypass mode. With most off-the-shelf d/a chips, you are stuck with their internal oversampling and using one of their internal digital filters. With the AK4497, it can be ran in non-oversamping mode and without having to use an internal digital filter, so I was able to implement an analog-domain filter in the JFET output stage that follows the d/a conversion.

Each channel of the L2 DAC is laid out on a dedicated PCB containing the AK4497 and analog output stage (along with various voltage regulators). A third board (on the bottom of the 3-board stack) contains the digital input stages, Xilinx FPGA digital buffer chip, femto reclock circuitry, as well as all the voltage regulators for the digital sections.

Rossi’s favoured filter setting was mine, too. No fuss, no muss. For the other two boxes, I chose one filter after much experimentation and stuck with it. The MQA filter on the Mytek was a favourite, a Bézier curve on the T+A. Rossi told me there was no MQA support for his DAC module and he wasn’t expecting to add it any time in the future. No matter, when Qobuz HiRes files are so damn good with virtually the same repertoire as Tidal HiFi MQA. For the record, there was no MQA support on the T+A DAC, either.

Beginning with ‘Dead Again’ from Thomas Newman’s American Beauty, my digital testbed of choice for many years, the DAC module delivered an unfatiguing sound with superb bass control and an enviable timbral array of percussion instruments. Marimbas, so difficult to record and replicate, sounded precise with solid wood, leading transients and a beautifully smooth decay. Bass performance matched the stand alone boxes easily.

Thorny orchestral music such as Ein Heldenleben (A Hero’s Life) by Richard Strauss sounded as good as originally recorded (Karajan/Berlin Phil/DG)—the battle sequence, which goes on far too long, sounded more interesting as the module unravelled the noisy goings on. Strauss (the hero of his piece) was seriously pissed at music critics and his musical enemies, and he lets them have it. At ffff. Unless the DAC is top notch, it’s always a bit of a congealed mess. The DAC module was trumps, here. Even quieter instruments like flutes and oboes were heard clearly under the fusillade of brass and percussion.

Renée Fleming’s new Decca album ‘Lieder’ sounded exquisite. Her subtle inflections, breath support, sexy siblilance, and her quiet intensity were portrayed beautifully. Voices of all styles and ranges sounded as expected from such a well designed digital device. So many rob the musicality; the essence of the voice. And when the module’s sound is being projected through its spectacular linestage mainframe, it’s an artistic brotherhood of the first rank.

Much like the two other recent DAC reviews, I auditioned the module with PCM files only. The module will decode your digital heart’s desire (except MQA). See the Specs above for the fullsome list. You’re pretty well setup for the foreseeable digital future.

Conclusion

The two comparative DACs sounded spectacular with the Vinnie Rossi L2 Signature Preamplifier—it’s a benchmark product. If you already have a DAC you like, try it first with the L2 Preamplifier. The preamp is so brilliant, you may end your journey right there—my first reaction listening to digital through it (with the Mytek DAC) was ‘it makes my digital sound like vinyl’. No higher compliment from me. But, if your DAC isn’t up to snuff, you can always purchase the module at a later date. Sell the cables you won’t need anymore, and you can buy the DAC module.

Much like the Phono module, the DAC module plays well above its cost in today’s price/quality ratio. It can win your heart on sound alone, but the fewer cables and lighter footprint may tip the scales in its favour. Highly recommended.

Further information: Vinnie Rossi