Kanex Pro HDMI Audio De-Embedder

tmallin

WBF Technical Expert
May 19, 2010
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Chicagoland
"What the heck is THAT?" I can hear you say. Don't worry, I'll explain.

I recently swapped out my Lyngdorf TDAI-2170 for a new Benchmark DAC-3 DX to perform DAC duties. The Lyngdorf is one of the few two-channel audio electronics boxes which has HDMI inputs (they are optional, but my unit has all the options). I had been feeding the Lyngdorf from the HDMI output of my Electronic Visionary Systems (EVS - Ric Schultz) fully modified Oppo BDP-105D.

I like to use the HDMI output from the Oppo because (1) it outputs a 24-bit rather than 16-bit signal from CDs and internet streaming sources, (2) it sounds a tiny tad better than the Oppo's coax digital output perhaps because of that, and (3) the Oppo's HDMI port outputs full resolution PCM signals from SACD (the Oppo gives the user a choice of PCM or DSD digital output from SACD sources) and high-res PCM sources like the Reference Recordings HRx discs and Blu-Ray Audio discs. The Oppo's coax output will not put out any signal for SACD or high-resolution PCM sources. Using the HDMI out eliminates the necessity of another D/A - A/D conversion for SACD and PCM high resolution sources which would otherwise have to come out of the Oppo's analog outputs and into the A/D converter of the Lyngdorf.

Since the Benchmark, unlike the Lyngdorf, does not accept HDMI output from my EVS-modified Oppo BDP-105D, I searched for a way to continue using the Oppo's HDMI output while feeding the signal into the Benchmark via coaxial SPDIF cable. I discovered that this sort of extraction of the audio signals from HDMI cable requires an active digital device called an audio de-embedder.

After reading reviews of various such devices, I've added the very tiny Kanex Pro Audio De-Embedder to my system. Note that the picture at that link shows two of the boxes stacked atop each other just so that you can see both the input side and the output side in the same photo. Besides this tiny box, the unit has a wall-wart power supply. This $70 unit works like a charm, accepting HDMI-based signals up to 24/192 at its input and outputting bit-perfect same format on SPDIF coax or toslink at its output. In my system the de-embedder's HDMI input is fed from the Oppo's HDMI output via Blue Jeans Belden Series FE cable and the de-embedder's coax SPDIF output feeds one of the Benchmark's digital coax inputs via coax Blue Jeans Belden 1694A digital coax cable.

The Benchmark's front panel display verifies that the digital signal arriving at the Benchmark through the Kanex is in the same format as what left the Oppo. There is no down-resolution. And, for CDs and other non-high-res digital sources, I can directly A/B the sound of the Oppo's digital coax output directly feeding a digital coax input of the Benchmark against the Oppo's HDMI output into the Kanex de-embedder and thence to another Benchmark digital coax input. All cables are the Blue Jeans mentioned above. The Kanex seems to be totally transparent. I hear the same tiny tad better sound via the Kanex path as I did with the Oppo directly feeding the Lyngdorf's HDMI and coax inputs. Not bad for a $70 device.

The Lyngdorf will accept DSD64 signals from SACDs. Thus, until I switched to the Benchmark, I could run DSD64 directly from the Oppo's HDMI output into the Lyngdorf's HDMI input.

Three operational notes about the Kanex: (1) The Kanex will not pass DSD signals, only PCM. Thus, to output SACD audio from the HDMI output of the Oppo through the Kanex, from the Oppo's menu system you have to choose PCM output for SACDs rather than DSD output. I am not aware of any HDMI Audio De-Embedder which will pass DSD signals. (2) To avoid down-resolution of the Kanex's PCM output, the bright light on the input side of the Kanex must be ON. The manufacturer's instructions about this are a bit unclear. That bright light can be toggled on and off by depressing the push button on the input side of the device. (3) You do not have to connect the HDMI output of the Kanex to anything. Thus, for the audio-only de-embedding, you only need to connect the Kanex to an HDMI cable on its input side. Again, the manufacturer's instructions, as well as the comments of other users, can be a bit obscure on this point.

I do bypass the Kanex when feeding the USB-based Enhanced Digital Output of my Logitech Squeezebox Touch into the Benchmark. That's not due to any problem with the Kanex, however. The Squeezebox's USB output clearly sounds better this way for some reason. With the Lyngdorf, it was a toss-up; there were small but definite differences in the sound of the Squeezebox fed into the Oppo's USB input and then to the Lyngdorf versus directly into the Lyngdorf's USB input. On balance, I preferred feeding it through the Oppo. Now the tables are turned and the Squeezebox definitely sounds more real feeding the Benchmark directly. It has never ceased to amaze me how good low-bit-rate internet radio streaming can sound through this now-long-discontinued Squeezebox Touch. A/Bing the sound of any internet radio signal I can stream through my i-Phone, i-Pad, Apple TV, or BlueSound Node with that same signal streamed through the Touch's USB Enhanced Digital Output always points out the clear superiority of the Touch. The Benchmark's treatment of USB inputs just enhances this superiority.

You may wonder why I swapped the Lyndorf for the Benchmark. That's another story, but suffice it to say here that, as good as the Lyngdorf is as a DAC and otherwise--and it IS outstanding sounding as well as being the Swiss Army Knife of digital preamps/integrated amps--as a DAC, the Benchmark with its new ESS 9028Pro DAC chips, sounds better, pure and simple. The Benchmark has a bit better bass definition and wallop, a yet-more-analog-like, yet more "relaxed" sound due to yet smoother, more filligreed, and more extended highs, as well as seemingly yet-greater clarity and yet-lower distortion.
 
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