K-01 Digital Source Device

    The Overview

    ESOTERIC releases the K-01, the flagship model of our all-in-one advanced D/A converter and Super Audio CD/CD player series, capitalizing on ESOTERIC's state-of-the-art technology and derived from our award winning P-01/D-01 series separates. It has been seven years since the debut of the original X-01, with its high-precision and high-rigidity VRDS-NEO SACD/CD transport mechanism. The X-01/X-03 series, which have stayed at the top of ESOTERIC's all-in-one SACD/CD player lineup, have been completely updated and make their debut as the all-new "K" series in November 2010. The design concept of the K series is extremely clear and simple -- a 2-channel D/A converter and stereo player that gives a stress-free musical experience, without adding or removing anything from the original source material. All aspects of the design and engineering process for the K series had extremely tough requirements to further advance ESOTERIC's top technology. Design and engineering was completed applying all of ESOTERIC's know-how in mechatronics technology, state-of-the-art audio technology, and evolutionary materials including DAC implementation, for which cost was not a consideration. The K series is committed to advancing the "state of the art" for the 2 channel audio purist, for both high resolution audio files and disc based audio playback applications.

    The K-01 is equipped with our new VRDS-NEO "VMK-3.5-20S" mechanism, which has advanced substantially beyond existing VRDS models. The K-01 follows the philosophy of the D-01, and has two 32-bit monaural D/A converters with eight parallel/differential DAC circuits used per channel, as well as separate L/R power supplies. The on-board, high-precision clocking circuit has also been advanced. The power supply for each circuit block has been optimized by using four on-board power transformers. Three sets of 192 kHz/24-bit digital inputs, supporting the most advanced high-sampling-rate digital sources are also built-in. USB driver software supports 192 kHz/24-bit asynchronous transmission for connecting with a PC. The K-01 responds to the stringent demands of music lovers and audio purists, for a top-of-the-line digital source, 2-channel playback device.

The Features

VRDS-NEO “VMK-3.5-20S” transport mechanism


 ESOTERIC’s proprietary VRDS-NEO transport mechanism uses a high-precision turntable for spinning Super Audio CD/CD discs, improving read precision by mechanically correcting for surface run-out. This is a comprehensive compilation of ESOTERIC’s high-end mechatronics technology. The K-01 uses an evolutionary version of the mechanism configuration adopted for the P-03 SACD/CD transport and now includes the VRDS-NEO “VMK-3.5-20S.” This new VRDS mechanism includes further refinements in the design of the driver circuit. In addition, the disc tray loader now includes a shutter mechanism, designed to reduce extraneous noise and airborne contaminants from entering or degrading the electromechanical operation of the system.
 The VRDS-NEO “VMK-3.5-20S” is a new high-quality mechanism using a set of ceramic ball spindle bearings. A duralumin turntable with micron-level accuracy and a 20 mm steel turntable bridge are used, resulting in a total weight of 5.2 kg (11.5 lbs). Additionally, the proven features of the VRDS-NEO, such as the strong neodymium-magnet-driven coreless three-phase brushless spindle motor, the thread feed control, (which has evolved from the philosophy of the P-0), and the shaft-sliding type pickup, where the laser beam consistently illuminates the disk perpendicularly, are all inherited by the K-01.

New VS-DD spindle servo driver circuit


 The driver circuit of the transport mechanism was newly designed specifically for audio playback, to accomplish smoother and higher-accuracy servo control. The VS-DD (VRDS Spindle Discrete Driver), a newly designed discrete amplifier circuit, is used to drive the spindle motor, which is the core of the VRDS-NEO”VMK-3.5-20S”.
 Special proprietary toroidal transformers are also used in the power supply. The discrete amplifier circuit optimizes the power supply output to the motors, to realize a smoother and more refined spindle drive. Additionally, a separate power supply is used for each power-consuming spindle motor, to eliminate any impact on the audio circuit and to achieve outstanding performance. This level of performance approaches the quality of a separate transport and DAC reference system.

VCXO high-precision clock


 A newly designed high-precision clock is implemented to achieve the highest level of sound quality for an all-in-one digital player. A VCXO (voltage controlled crystal oscillator) of +/- 0.5 ppm (*2) that uses a large crystal is deployed in the K-01, which is very advantageous for advanced sound quality.
 Additionally, a stabilized power supply circuit improves the stability of clock circuit operation. When using the K-01 without using an external WORD clock, the high precision audio clock sync signal generated by the VCXO is directly delivered to the D/A converter, without passing through the PLL circuit. This enables higher-quality reproduction that is a step ahead of standard designs. This also substantially reduces any audible jitter when transmitting audio signals to achieve high-speed and high-quality reproduction inclusive of a very dramatic presence and acoustic delicacy.
(*2) Factory setting

High-quality discrete buffer circuit with a high voltage power supply

 A discrete buffer output circuit with a high voltage power supply of +/- 22 V has been deployed for the analog audio output, following the technology used in the D-01. Full use is made of the exceedingly high drive capability and slew rate to provide a stress-free playback capability for various signals, from miniscule signals to high-power output. These powerful discrete buffer output circuits are laid out symmetrically for each of the hot/cold signal lines to construct a rich and fully balanced configuration for XLR audio outputs. Additionally, a parallel buffer output configuration is implemented to switch the buffer amplifier to a parallel configuration, when RCA audio outputs are used. These enhancements provide advanced circuitry with the best sound quality for each of the balanced and unbalanced signal outputs.

Four types of digital filters and digital filter “Off” mode

 The K-01 features four types of digital filters for PCM signal processing. In addition to two types of FIR digital filters that have a reputation for outstanding sound quality, two types of short delay digital filters are featured. These filters, often referred to as apodizing filters, eliminate the pre-echo and ringing effects in the impulse waveform to reproduce the audio signal as a more nature and precise sound, void of the artifacts often associated with CD recording. The Digital Filter Off mode, which bypasses all 4 of the digital filters, is also provided. You can select any of the digital filters or the off mode according to your preference.

Three digital input systems to support a high sampling rate

 Even when you use the K-01 as a discrete D/A converter for a high-sampling-rate source, the K-01 makes the most of the astonishing quality of its 32-bit dual mono D/A converters. The K-01 features three systems of input (USB, coaxial and optical), and these digital inputs support high-sampling-rate sources up to 24 bit/192 kHz.


USB input supporting asynchronous transmission and 24 bit/192 kHz sources enables high-quality reproduction of music stored on a PC

High-sampling-rate sources of studio master quality can be input at their original resolution, by connecting the K-01 to your PC through a USB port. To ensure a precise high-end design for the USB connection, ESOTERIC developed proprietary driver software (the driver software can be downloaded from the ESOTERIC website). The USB input supports high-quality asynchronous transmission and the input of high-sampling-rate sources to 24 bit / 192 kHz. Three transmission modes, including two types of high-speed transmission (including asynchronous transmission), and the standard full-speed mode, are also provided to enhance compatibility with a wide variety of PCs and operating systems.
 Additionally, an Esoteric USB isolator, isolates the power and signal paths from the USB input system. This isolator eliminates interference from external devices, including the PC, to clearly reproduce high-resolution music files without loss of fidelity.
* Note: Reproducible formats depend on the music player capabilities installed on the PC.

The Specs

Compatible disc types
Super Audio CD, CD (CD-R/CD-RW compatible)
Analog audio output
Jacks XLR jacks (2 channel) x 1
RCA jacks (2 channel) x 1
Output impedance XLR: 100 ohms
RCA: 47 ohms
Maximum output leve
(1 kHz, full scale, 10 k ohms)
XLR (Gain: 0 dB): 2.45 Vrms
RCA: 2.45 Vrms
Frequency response 5 Hz to 55 kHz ( 3 dB)
Signal-to-noise ratio (S/N) 115 dB
Total harmonic distortion 0.0015% (1 kHz)
Digital audio output
Coaxial RCA jack x 1 0.5 Vp-p/75 ohms
Digital audio input
Coaxial RCA terminal x 1 (input impedance 75 ohms)
Optical digital terminal x 1 24.0 to 14.5 dBm peak
USB port B connector USB 2.0 / 192 kHz-24 bit async.
Word synchronization input format
Jack BNC
Input impedance 75 ohms
Input level Rectangle wave: equivalent to TTL levels
Sine wave: 0.5 to 1.0 Vrms/50 to 75 ohms
The K-01 can accept and synchronize to the following frequencies received from external clock devices: 44.1 kHz, 88.2 kHz, 176.4 kHz, 10 MHz (the accuracy of locking range limited within ±15 ppm)
D/A Converter
K-01 32bit AK4399 x8 DACs / per channel
Power supply
Power supply EUROPE AC 230 V, 50 Hz
USA/CANADA AC 120 V, 60 Hz
KOREA AC 220 V, 60 Hz
Power consumption 33 W
External dimensions
(W x H x D)
445 x 162 x 438 mm (17 1/4" x 6" 3/8 x 13 1/4") (including protrusions)
Weight 31 kg (68 3/8 lbs)
Accessories Remote control unit (RC-1156) x 1
Batteries (AA) x 2
Power cord set x 1
Felt pads x 3
Owner's manual x 1
Warranty card x 1
- This product is available in three different power supply variations shown in the chart above. Make sure that the voltage shown on the rear panel matches the AC line voltage in your area.
- The shape of the AC inlet and plug of the supplied power cord depends on the voltage rating and destination country.