Digital Processor Reviews

In Gramophone Dreams #88, I described the sound of TEAC's VRDS-701T CD transport as "dense and precise in a way I had never previously heard from digital." I went on to explain, "by 'dense,' I mean there was a tangible corporeality effected by seemingly infinite quantities of small, tightly packed molecules of musical information."

What I noticed most during the review period was the extraordinary volume of data the 701T was vacuuming off those pits and lands and turning into music. As I have gotten to know it better, what I've noticed most is how the 701T sorts and delivers all that data in a manner that makes every DAC I pair it with sound more corporal and dynamic.

As I wrote that review, I wondered how the 701T would perform partnered with its matching UD-701N converter/streamer/preamplifier and how the TEAC flagship DAC's sound character would compare to flagship DACs from HoloAudio, Denafrips, and dCS.

Now I know. These are my impressions.

Description
The TEAC UD-701N ($4299.99) is the heart of a trio of matching 700-series components that includes the VRDS-701T CD transport and the smart-looking AP-701 power amplifier. The UD-701N isn't just a DAC; it's also a fully balanced, two-input (RCA + XLR) line-level preamplifier and a two-output headphone amplifier (4-pin XLR and ¼" jack).

The DAC part of the UD-701N isn't just another chip DAC. TEAC explains: "Instead of using a generic DAC [integrated circuit], we incorporated a custom-developed TEAC ΔΣ (Delta Sigma) discrete DAC comprised of discrete circuitry that uses FPGA"—field-programmable gate array—"incorporating our original algorithms." See the block diagram below.

"DSD signals are transmitted as is, while PCM signals are transmitted after passing through a ΔΣ modulator and conversion to either 1-bit or multibit signals, according to the end user's choosing." Multibit is the default. "With the TEAC ΔΣ discrete DAC, playback of 22.5MHz DSD and 384kHz/32-bit PCM is possible." Up-conversion can be used with all digital inputs and comes in three powers: 2×, 4×, or 8×Fs. Users can also set the ΔΣ sampling frequency: 128×, 256×, or 512×Fs.

TEAC's signature antivibration strategy is evidenced by its four minimally attached "floating" toroidal power transformers, one for each channel's fully balanced high-current analog section—the 701N is truly dual-mono—one for the network module, and one for the digital-control sections.

The 701N's feet contribute further to that low-vibration strategy. "TEAC's three pinpoint feet utilize a new mechanism that provides protection on the bottom panel to suppress vibrations that ultimately affect audio quality. Even the length of the side fins of the device that are for heat dispersion have also been adjusted to prevent sympathetic vibrations."

Most digital components either ignore vibration-induced nonlinearities or throw mass and rigidity at the problem. TEAC's UD-701N and VRDS-701T opt for a strategy I regard as more elegant. It may also be more effective.

The 701N's brushed-aluminum front panel matches that of the VRDS-701T transport and the AP-701 amplifier. It's a timeless-looking facia that will work aesthetically in a serious audiophile rack, on a bureau top in a luxury home, or in a professional recording studio. Its semifaux "rack handles" keep the component from looking generic and contribute to the 701N's ability to look at home in diverse environments.

I enjoyed the assurity of the front panel's mechanical power/standby switch. The feel of the centrally located selector knob and far right volume knob scream luxury and tight-tolerance manufacturing. In my room, where I often listen near enough to reach forward and turn these knobs, the OLED display seemed just the right size and color: discrete and professional, like an experienced waiter in a fine restaurant.

In use, the 701N exhibits a strong sense of drive, which TEAC attributes to its output-buffer circuits. "We used TEAC-HCLD2 circuits, which are improved versions of our TEAC-HCLD (TEAC High Current Line Driver) enhanced-current output buffer circuits. These raise the current transmission capabilities that are important in analog output circuits. Each channel has a positive and negative two-circuit structure with diamond buffer amplifiers, which have high current transmission capabilities, used as line drivers. Drive is differential for balanced output and parallel for unbalanced output. By increasing the current supply ability, transmitting the dynamism of audio signals without loss becomes possible."

My suspicious nature urged me to email the never-sleeps public relations ball-of-fire Jaclyn Inglis of Jaclyn Inglis PR & Communications. She facilitated my TEAC DAC investigations by asking TEAC's engineers to verify that the analog input signals remained analog all the way through, including to the headphone outputs.

"Yes, all analog inputs are all analog all the way through. The signal path does not have any analog to digital conversion."

The volume control is all-analog; TEAC describes it this way: "Our TEAC-QVCS (Quad Volume Control System) is a variable gain amp volume control (see block diagram) with four independent circuits for left, right, positive, and negative (L+, L–, R+, and R–)." During these auditions, the 701N provided sufficient gain to drive all three of my amplifiers directly. If you're using it with a preamplifier, the volume control can be bypassed and the fixed output set to either 2V or 4V.

The 701N offers Bluetooth including the LDAC, LHDC, AAC, SBC, aptX, and aptXHD audio codecs; I didn't use Bluetooth. It is also Roon Ready.

The 701N's aluminum and plastic remote is simple to use and solidly built. There's a custom application for Windows and Mac computers—TEAC HR Audio Player—and an app for smartphones and tablets: TEAC HR Streamer, available for iOS and Android. The Streamer app is bare bones but very good: easy to install and intuitive to use. It's available for iOS and Android.

Listening via the analog input
The first test recording I played with the UD-701N DAC/Network player was the LP Felt by Nils Frahm (Erased Tapes Records ERATPO33LP). I used this reverb-drenched contemporary recording to assess how the 701N's line-level input handles transients and reverb tails and how invisible the preamp section was. It was clear by the end of the first album side that notes from Frahm's piano were not blurred or foreshortened. This completeness allowed the carefully constructed space of Frahm's recording to occupy my space with the same level of immediacy and transparency it did while playing this recording through the TEAC DAC into the HoloAudio Serene preamp. The only discernable difference between the TEAC alone and with the Serene between it and the First Watt SIT-4 amplifier was the quality of "finish" on the sound energy. Driving the SIT-4 directly, the 701N put a nice semigloss on the sound. Signals coming out of the Serene exhibited an equally clear but more satiny finish.

When tube-fired analog signals—like those from PrimaLuna's 10-tube EVO 100 phono stage—pass through HoloAudio's solid state Serene preamp, they do not come out sounding hard or transistorized. Instead, they come out sounding almost the same as they do coming out of PrimaLuna's eight-tube EVO 400 line-level preamp. The 400 pre adds a teaspoon of reverberant "juice" that wets the transparency, but in a casual blind test, I doubt I could guess which preamp was playing. I'm pretty sure I could distinguish between those preamps and the 701N's output. The UD-701N plays substantially more firmly and forcefully than the Serene or the EVO 400. That forcefulness would be a strong tell.

In my system, the 701N's analog stage played LPs with unusually deep, perfectly tuned bass; a task that was likely assisted by First Watt's new SIT-4 power amplifier, which applies a just-right, never-too-tight grip on my Falcon's woofers. No matter how we divvy up the credit, with the 701N direct-driving the SIT-4, my Gold Badge LS3/5a's went lower in the bass (possibly below 50Hz) and pushed it out harder and tighter than I ever imagined possible. Bass was suddenly something I could follow and pay attention to. The listening impact of this deeper, tighter, more forceful bass was quite pronounced, and totally enjoyable.

Listening via S/PDIF
With every DAC I tried, the 701T was so neutral tonewise, so thoroughly excavated data-wise, and so well-formed space-and contrast-wise that I decided it would be the perfect source for evaluating DACs. After trying all my reference DACs, I began my TEAC 701T + 701N auditions by spinning the best-sounding CD I own: M•A Recordings' Serà una Noche: Otra Noche (MA092A). I figured if that source-combo sounds dry, or less than ultra-vivid and super-3-D, this story wouldn't end well. I was expecting Everest-level digital sound and, fortunately, that is what I heard.

The first thing I noticed was how those first dramatic notes at the start of track one, "Viejo Ciego," exposed the complete volume of the recording venue. The detail and hyperclarity of Otra Noche's echo and reverb dominated the drama—as did the flawless vocal and instrumental tones. Santiago Segret's bandoneon, Marcelo Moguilevsky's clarinet, and Lidia Borda's voice projected large, clear, and extraordinarily present in my room. This was exactly the kind of big, well-drawn, lock-me-on sound I am always hoping to find.

Then again, Otra Noche is the finest digital recording I know. It would sound moving and three-dimensional coming out of a boom box. As one of my old pals used to say, "Your hi-fi is only as good as how it plays your worst record." I can't think of a "worst" record, but I do have some CDs containing good music but with sound that is off in a way that prevents my full engagement. One of those is a 1997 collection of American folk music called American Primitive Vol.1: Pre-war Gospel (1926–1936) (Revenant RVN 206).

Despite their vintage, the mostly electric recordings in this nicely mastered collection sound crisp and clean and not muffled. Obviously, producer John Fahey saw to it that their raw expression was not smothered by soul-crushing noise reduction. Unfortunately, my Onkyo C-7030 CD player blurred, dulled, and failed to resolve most of the low-level background sounds that describe the recording site. This canceled any hope for audio verité and made getting into the songs difficult. Fortunately, TEAC's 701T transport + UD-701N DAC located all the data the Onkyo lost and put it in precisely ordered focus. The beats and rhythms and inner details of these recordings came through in a manner that was easy to notice and appreciate.

The greatest virtue of this TEAC combo was how different it allowed each singer's voice to sound. It did this by laying out clearly their unique harmonic palettes and fully exposing the nuanced particles of pace and inflection. I regard this as evidential proof of these components' accuracy.

TEAC's VRDS-701T transport feeding TEAC's UD-701N DAC-preamp through Kimber Kable's D60 coaxial cable played all my favorite CDs with what I currently regard as leading-edge resolve.