ESOTERIC | K-01X — SUPER AUDIO CD PLAYER
Taking Sound to the X Dimension
X is the unknown. “X” in a model name symbolizes the ultimate advancements of technology, craftsmanship and creative commitment.
The K-01 and K-03 have won high acclaim as leaders of Esoteric’s line of all-in-one Super Audio CD players, and their extraordinary ability to reproduce the essential qualities of a musical performance continues to enthrall listeners to this day.
Now, a new “X” inherits that solid pedigree and further refines these qualities in the new K-01X and K-03X Super Audio CD players. Concentrated beauty in an all-in-one form is a hallmark of Esoteric’s flagship Grandiose models. The philosophy and technologies found in these high-end digital players reveal a new dimension of sound appreciation unlike anything you have ever experienced before.
A New Pinnacle of Sound Quality
Four years after the release of the K-01—the world’s leading all-in-one digital player—the new K-01X debuts as a more compact version of Esoteric’s flagship Grandiose model. Utilizing the same type of highly rigid chassis construction as the Grandiose and a similar four-transformer power supply, it integrates the Grandiose P1’s high-precision VRDS-NEO “VMK-3.5-20S” turntable with two independent monaural DAC units derived from the Grandiose D1 design, each configured with a parallel array of 8 individual converters, which are summed to optimize linearity and minimize noise.
Electronic circuitry has also been further improved with the latest technologies, including a new AK4495S DAC IC, an advanced 35-bit D/A processing algorithm, an HCLD buffer amp, a DSD-compatible USB interface, and a large, low phase noise clock, all ensuring the K-01X achieves the absolute pinnacle of sound quality.
Chassis Construction and Parts Layout
The VRDS-NEO transport mechanism is positioned in the center of the unit, directly attached to the 5 mm-thick steel chassis bottom, and is supported at three points by Esoteric’s proprietary pinpoint feet (Patent No. 4075477) to effectively suppress the effects of vibration on the turntable mechanism. The chassis interior features a double-deck construction with five compartments. Each circuit block is isolated within its own compartment to minimize interference between circuits. Two separate audio boards for each channel are positioned nearest the rear terminals. The audio power circuitry and power transformers are also isolated from the audio boards, and the power supply wiring has been made as short as possible to minimize the influence of magnetic flux leakage, vibration, and the like.
The K-01X features four large-capacity toroidal transformers: one for each of the two built-in monaural D/A converters, one for the audio circuitry, and one for the VS-DD spindle servo driver. The K-03X is equipped with two large-capacity toroidal transformers: one for the analog circuitry and the other for the digital/mechanism drive circuitry. This design provides ideal power supply capability to all circuit blocks without interference.
The culmination of Esoteric’s most advanced mechatronics know-how, the VRDS system radically improves the reading of Super Audio CD/CD discs by mechanically correcting for surface run-out. The K-01X’s VRDS-NEO VMK-3.5-20S drive also features two sets of specially selected ball bearings supporting a duralumin turntable constructed to micron-level accuracy, and a 20mm-thick steel turntable bridge. The combined mechanical structure weighs an impressive 5.2kg (12kg including the rigid base).
The drive employs proven Esoteric technologies, including a high-flux-density magnet-driven careless three-phase brushless spindle motor, a thread feed control derived from the thinking behind the P-0, and a shaft-sliding pickup which consistently illuminates the disk with a precisely perpendicular beam of laser light. Additionally, the disc tray features a silent shutter mechanism* that further ensures the ultimate in operating precision.
VS-DD* Spindle Servo Driver and Proprietary Toroidal Power Supply
At the heart of the VRDS-NEO drive is a spindle driven by Esoteric’s proprietary VS-DD servo driver circuit. This uses a discrete three-channel amplifier to optimize the motor drive current, minimize vibration and provide ultra-smooth spindle operation and high-accuracy servo control. The K-01X is also equipped with a proprietary toroidal power supply that greatly enhances noise isolation.
Grandiose D1 Lineage Dual Mono D/A Converters with Separate Left and Right Channel Power Supplies
The D/A converter uses the same design philosophy as our Grandiose D1. Incorporating Asahi Kasei Microdevices Corporation’s 32-bit AK4495S DAC IC and MUSES 02 operational amplifier,* this exceptional DAC uses 8 parallel/differential circuits with 16 outputs driving each channel to achieve outstanding linearity and low distortion.
Like the Grandiose D1, this D/A converter also features fully independent power transformers and power supply circuits for each channel to create a true dual mono configuration. The generous power supply capacity and total channel separation enabled by this arrangement provides excellent dynamics, with realistic stereo imaging and exceptional resolution of fine detail.
High-Bit D/A Processing With Outstanding Powers of Musical Expression
Both the K-01X and K-03X combine multiple 32-bit DAC chipsets and utilize a high-bit D/A processing algorithm to convert the PCM signal to analog at a high resolution in excess of 32 bits. The K-01X supports 35-bit processing and the K-03X 34-bit processing. 35-bit processing achieves an astounding resolution that is fully 2,048 times that of 24-bit processing (34-bit processing being 1,024 times that of 24-bit processing). In the digital range, full advantage is taken of high-bit data gradation to minimize calculation errors and provide faithful conversion to analog, thereby attaining outstanding powers of expression with even extremely small music signals.
Esoteric-HCLD*: Esoteric’s Proprietary Current-Enhancing Output Buffer Circuit
The ability to produce comparatively large currents and high slew rates are two of the most important factors to enable an analog output circuit to accurately transmit the wide dynamic range of a music signal without degradation. To obtain the ultimate performance, the K-01X employs the same Esoteric-HCLD buffer amplifier circuitry found in the Grandiose D1. Two of these buffer circuits are employed per channel. Their high output current capacity and exceptionally fast slew rate (2000V/s) provide an indication of their excellent response speed. By configuring them differentially to drive the XLR outputs and in parallel to drive the RCA outputs, the instantaneous output current available is maximized. The Esoteric-HCLD circuitry enables the K-01X and K-03X to recreate the full dynamism of music with a sense of realism that will take your breath away. *HCLD = High Current Line Driver
Comprehensive D/D Conversion Compatible with Wide Range of Sources
In addition to playback at the original sampling frequency, 2X, 4X and 8X up-conversion of the PCM digital signal is also provided. A range of D/D conversion modes are also available for the PCM format, such as PCM-to-DSD conversion.
Four Types of Digital Filters and a Filter OFF Mode
Four types of digital filter can be freely selected for PCM signal processing. Besides two FIR digital filters, which have an established reputation for providing outstanding sound quality, two types of short delay digital filters are also included for a more precise and natural sound. All four digital filters for both PCM and DSD can be bypassed by selecting the Digital Filter Off mode.
Digital Inputs Support DSD (DoP format) and High-Res PCM
Three digital inputs (USB, coaxial, and optical) enable connection to a wide range of systems. Coaxial and optical inputs support DSD in DoP format and high-resolution PCM of up to 192 kHz/24-bit.
USB Support for 2.5/5.6 MHz DSD, 384 kHz/32-bit PCM, and Asynchronous Transmission
The USB input supports asynchronous transmission and rates up to 2.8/5.6 MHz DSD and 384 kHz/32-bit PCM. Esoteric’s original PC driver software achieves outstanding playback of even studio-master-quality source files. DoP and ASIO 2.1 are also supported.
High-Precision VCXO Clock
Often considered the heart of a digital player, the clock circuit supplies a high accuracy reference clock signal to the digital circuitry. Its voltage-controlled crystal oscillator (VCXO) was originally developed for the Grandiose P1/D1 in a joint effort with Nihon Dempa Kogyo (NDK), a major manufacturer of crystal oscillators. As a high-precision custom clock worthy of the world’s leading equipment, this circuit ensures exceptional sound playback quality thanks to an exceptionally large crystal element with excellent center accuracy (±0.5 ppm*) and extremely low levels of phase noise (*at time of shipping).
Clock Sync Function for Synchronization with External Devices
Connecting the unit to a high-precision master clock generator (G-01, G-02) allows synchronization of the unit’s operation with an external clock signal, thereby enabling the sound quality of the system to be upgraded. Input frequencies are 44.1/88.2/176.4 kHz, as well as 10 MHz and 22 MHz direct master clock linkage.* Synchronization with external clocks is also supported when the USB input is used. (When an external clock generator is connected, its signal is also used to clock the D/A converter, bypassing the internal PLL circuit and providing higher precision D/A conversion.)
The analog audio outputs can be switched between RCA, XLR, and OFF. Hot 2 or Hot 3 XLR pin assignments can also be selected.
Support for Future System Upgrades
RCA (S/PDIF) or XLR (AES/EBU) digital outputs are provided. These allow to player’s performance to be upgraded by the addition of a top-end Esoteric D/A converter. *This circuit can be turned off when digital output is not in use.
Analog Audio Outputs
Maximum Output Level*
Total Harmonic Distortion**
XLR Connector (2ch) ×1 | RCA Connector (2ch) ×1
XLR: 40Ω | RCA: 10Ω
(1kHz, full-scale, into 10k) XLR: 4.8Vrms | RCA: 2.4Vrms
5Hz to 40kHz (-3dB)
K-01X: 117dB | K-03X: 116dB
K-01X: 0.0006% (1kHz) | K-03X: 0.001% (1kHz)
*Output Level Drops 3dB for DSD Data Playback when DSD Filter is Off.
**Super Audio CD, XLR Analog Output
Digital Audio Output
XLR Connector x 1
RCA Connector x 1
3 Vp-p (into 110Ω)
0.5 Vp-p (into 75Ω)
Digital Audio Input
RCA Connector x 1
Optical Digital Connector x 1
(input impedance 75Ω) 0.5 Vp-p
-24.0 to -14.5dBm Peak
USB 2.0 Standard
Clock Sync Input Format
Supported Input Frequencies (±15ppm)
44.1, 48, 88.2, 96, 176.4, 192kHz,
10, 22.5792, 24.576MHz
Rectangle Wave: Equivalent to TTL Levels;
Sine Wave: 0.5 to 1.0 Vrms (50Ω to 75Ω)
External Dimensions (W x H x D, including protrusions)
AC 230V, 50Hz | AC 120V, 60Hz | AC 220V, 60Hz
K-01X: 27W | K-03X: 25W
445 ×162 × 438 mm (17 1/4 × 6 3/8 × 13 1/4in)
K-01X: 31kg (68 3/8 lbs) | K-03X: 28kg (61 3/4 lbs)
Power Cord Set
Remote Control (K-01X:RC-1315 | K-03X:RC-1301)