Teac UD-701N USB DAC/Network Audio Player (Silver)

Instead of using a generic DAC IC, TEAC incorporated a TEAC ΔΣ (Delta Sigma) discrete DAC comprised of discrete circuitry that uses FPGA incorporating their original algorithms. Analog signals are output with high audio quality. DSD signals are transmitted as is, while PCM signals are transmitted after passing through a ΔΣ modulator and conversion to either 1-bit or multi-bit signals; according to the end users choosing.

We can say that achieving this wide, perfectly clear sound field, which can be realized specifically because of the discrete design, is TEAC reaching the pinnacle of its sound objectives.

With the TEAC ΔΣ discrete DAC, playback of 22.5MHz DSD and 384kHz/32-bit PCM is possible.

TEAC has incorporated a best-in-class dual-mono structure throughout the unit, from the power circuit with independent left and right toroidal core transformers to the D/A converter section and analog output stage.

This dual-model structure, which has complete mono circuits for each of the two channels, prevents interference between the left and right channels, enabling the realization of rich musical expression that reproduces the sense of space and dimension.

The fully balanced transmission of both the left and right analog output signals from after D/A conversion through the final output stage improves the signal-to-noise ratio and the dynamic range. This conveys signals in a purer state without losing the sense of air that high-resolution audio sources have.

In addition to the two toroidal core transformers for the independent left and right analog signals, separate toroidal core transformers are also used in both the network module and digital control sections. In particular, stable electricity is supplied to the network module, which requires advanced processing, by strengthening the power supply for the network module section with linear power.

Not only as a USB DAC/Network player that employs two sets of coaxial and optical digital inputs, but the UD-701N also works as a high-quality analog preamplifier by employing additional analog audio inputs via RCA and XLR connectors that allow users to connect conventional audio sources.

TEAC's TEAC-QVCS (Quad Volume Control System) is a variable gain amp volume control with four independent circuits for left, right, positive, and negative (L+, L−, R+, and R−). Placing this in the audio signal route makes it as short as possible, preventing the degradation of audio signals caused by drawing them through signal lines. Moreover, since the volume can be adjusted in extremely fine 0.5 dB intervals, you can achieve the ideal volume for the audio system or headphones that you are using.

TEAC used TEAC-HCLD2 circuits, which are improved versions of their 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.

A total of four diamond buffers, one in each of the left, right, positive, and negative circuits, are used in the dedicated headphone amplifier, enabling the connection of balanced drive headphones. Moreover, even during single-end use, by driving these amps in parallel, they can provide a stronger drive than ordinary single-end headphone amplifiers. This enables the potential of many types of headphones, including 600Ω high-impedance headphones, to be realized.

MQA (Master Quality Authenticated) is a high-quality audio codec that enables playback at the same quality level as studio masters. The UD-701N has an MQA decoder that controls D/A-converted waveforms with precision as fine as 5 ms in order to achieve analog waveforms that are true to the original recordings. Playback sound that seems like the original to the human ear can be achieved by greatly reducing the sound blurring that occurs easily when sounds start suddenly and at other times when sound pressure differences are extreme.

Since a full decoder is included, in addition to file and network playback, MQA data from digital inputs can also be decoded. Playback of MQA CDs is possible by connecting the digital output of a CD player to the UD-701N.

The upconversion function uses RDOT-NEO (Refined Digital Output Technology NEO) to smoothly augment PCM digital audio signals and upconvert their sampling frequencies 2, 4, or 8 times (384kHz maximum). RDOT, which applies an analogous interpolation method using fluency logic, is a technology that was developed to enable reproduction and playback of frequencies higher than 20 kHz that are lost by 44.1kHz/48kHz digital signals. Based on the information read, analogous data is generated between the waveform samples, which also results in data above 20 kHz.

In addition to the LDAC and LHDC codecs, which can transmit audio data with quality that is considered high resolution (96kHz/24-bit), it also supports Qualcomm aptX HD, which is capable of 48kHz/24-bit transmission. Of course, the popular AAC, Qualcomm aptX, and SBC codecs are also supported, so you can easily enjoy high-quality wireless playback from smartphones and digital audio players.

With a wired network connection, Smart Home apps can be used with the UD-701N, which also supports this platform. Moreover, playlists on the UD-701N can be managed using TEAC HR Streamer and other control apps that support OpenHome. Gapless playback is also supported.

With support for Roon Ready, functions provided by RAAT (Roon Advanced Audio Transport), including high-quality audio playback, easy and convenient operation using apps, and multi-room synchronized playback can be used without limits.

Along with Spotify Connect, this model also supports Tidal and Qobuz, which are subscription music streaming services that enable listening to lossless CD-quality (44.1kHz/16-bit) recordings.

When transmitting large amounts of digital data by USB cable from high-resolution audio sources, large inconsistencies arise in the processing loads of both the sending computer and the receiving USB DAC, and audio dropouts and other problems can occur. Using the Bulk Pet USB transfer technology, however, the same amount of data is transmitted at a steady rate, leveling the processing loads of both sides and realizing stable data transmission. Since changes in computer load conditions can also affect audio quality, you can select from four preset transmission modes to choose your preferred audio quality.

A floating structure is utilized to keep transformers, which can easily cause vibrations, isolated from the bottom panel. The lengths of all the side fins, which are for heat dispersion, have also been adjusted to prevent sympathetic vibrations.

In addition to using the minimum number of circuit board attachment screws, TEAC original pinpoint feet that utilize a new mechanism to provide play where they contact the bottom panel is used to thoroughly suppress vibrations that affect audio quality.