ONIX Zenith XST20 is an SACD transport designed for the playback of CDs, SACDs and MQA through a dedicated mechanism. The product uses a Sanyo HD870 CD mechanism and provides several digital outputs, including I2S over HDMI, BNC, AES/EBU over XLR, coaxial, Toslink optical and USB-A. This allows the connection to be selected according to the DAC or digital equipment used in the system.

The term transport identifies a device intended to read the disc and send the digital signal to an external device. The XST20 is therefore not presented as an amplifier or as an integrated DAC: its role is to read compatible discs and provide the signal through the available outputs. To complete the chain, an external device connected to one of the transport’s outputs is required.

CD, SACD and MQA Playback

The mechanism of the ONIX Zenith XST20 supports three types of content indicated in the product data: CD, SACD and MQA. SACD support makes the XST20 a solution aimed at music enthusiasts who wish to use a dedicated digital source for disc playback, while the declared compatibility with CD and MQA allows multiple formats to be handled within the same device.

Playback is handled by the Sanyo HD870 mechanism. This element is an integral part of the transport’s configuration and is the component responsible for reading the inserted disc. No further data is provided regarding the mechanism’s operating modes, so it is appropriate to adhere to the declared information: the XST20 is a transport for CD, SACD and MQA equipped with a Sanyo HD870 mechanism.

The availability of multiple digital outputs makes it possible to choose the connection according to the inputs of the downstream equipment. The I2S output, for example, provides a dedicated configuration with specific settings; the BNC, AES/EBU, coaxial, Toslink and USB-A outputs instead expand the integration possibilities with different digital devices. Actual compatibility depends on the inputs available on the DAC or connected device.

Configurable I2S Output

One of the XST20’s most relevant features is the I2S output over HDMI. Firmware V2.0 added a new setting dedicated to the I2S output, intended to increase compatibility with certain third-party DACs. This function is particularly useful when the connected DAC requires a specific I2S signal configuration.

The firmware also introduces an option relating to the 5 V voltage of the I2S Mute pin. The option can be enabled in the I2S output settings. This parameter makes it possible to adapt the output’s behaviour to certain connection requirements, without attributing universal compatibility to the function: results depend on the DAC used and its configuration.

The available data indicates that this setting is necessary for some DACs, including some older Topping models. The wording refers to specific devices and not to all DACs from the brand. Before choosing the I2S connection, it is therefore advisable to verify the requirements of the external DAC and the configuration required by its input.

Why the I2S Setting Is Important

I2S is not implemented identically by all manufacturers. For this reason, a configurable output can help manage differences between connected devices. In the case of the XST20, firmware V2.0 adds a specific adjustment for compatibility with third-party DACs and a dedicated choice for the 5 V Mute pin. These functions are mainly intended for users with a digital system in which an I2S connection is a practical option.

Other Digital Outputs

In addition to I2S, the ONIX Zenith XST20 provides the following outputs:

• BNC;
• AES/EBU over XLR;
• coaxial;
• Toslink optical;
• USB-A.

This equipment allows the transport to be connected to external devices fitted with corresponding digital inputs. The AES/EBU output uses an XLR connector, while the optical output uses the Toslink format. The presence of BNC and coaxial adds further alternatives for transmitting the digital signal. The most suitable output should be selected according to the connections actually available on the DAC or receiving device.

An USB-A output is also present. When the USB output is used, the XST20 automatically pauses playback if the USB DAC is disconnected. This behaviour directly manages the loss of the connection: instead of continuing playback without the connected DAC, the device temporarily stops operation.

Firmware V2.0

The firmware version indicated for the product is V2.0, with an update dated 28 May 2025. The reported changes mainly concern output management, interaction with the USB DAC, the power button and screen control.

In addition to the new I2S setting and the option for the 5 V Mute pin, the firmware indicates an optimised output switching. This change concerns switching between the different outputs available on the transport. No further details are provided regarding the operating conditions or switching procedure; the data nevertheless confirms that output management has been revised.

The behaviour of the power button has been adjusted. With version V2.0, the XST20 can be switched on either by a single press or by a long press. This dual mode allows the control to be used according to the preferred method, while retaining both options indicated by the manufacturer.

The screen power-on and power-off function has also been adjusted for the remote control and the main button. The firmware therefore affects screen-related commands through these two control systems. No further information is available regarding duration, brightness or visual settings, which are consequently not attributed to the product.

System Integration

The XST20 is intended for users who wish to integrate a dedicated SACD transport into a digital chain consisting of a disc player and an external DAC. The presence of numerous outputs allows the connection to be assessed according to the available input: I2S over HDMI, BNC, AES/EBU over XLR, coaxial, Toslink or USB-A.

For users of an I2S-compatible DAC, the firmware V2.0 settings may be relevant, especially when using third-party devices or some older Topping DACs. For USB users, the automatic pause behaviour in the event of DAC disconnection provides defined management of the interrupted connection. In every configuration, it is necessary to verify the correspondence between the output selected on the XST20 and the input available on the external device.

Identification Data

The product belongs to the ONIX brand and its full name is ONIX Zenith XST20. The product code is XST20. The declared weight is 9 kg. These data identify the model and help distinguish it within the system configuration or catalogue.

In summary, the ONIX Zenith XST20 is a transport for CD, SACD and MQA with a Sanyo HD870 mechanism, numerous digital outputs and a configurable I2S HDMI output. Firmware V2.0, updated on 28 May 2025, adds settings to improve compatibility with some third-party DACs, including some older Topping models, introduces the 5 V I2S Mute pin option and updates several device controls. The connection should be selected according to the DAC and the inputs actually available.

Main Features

• Product type: SACD Transport
• Firmware update date: 28 May 2025
• Firmware version: V2.0
• I2S compatibility: Increased compatibility with some DACs, including older Topping DACs
• I2S Mute pin voltage: 5 V, configurable option
• I2S output: Present; includes a new setting for compatibility with third-party DACs

Technical Specifications

Weight	9.0000
Product type	SACD Transport
Firmware update date	28 May 2025
Firmware version	V2.0
I2S compatibility	Increased compatibility with some DACs, including older Topping DACs
I2S Mute pin voltage	5 V, configurable option
I2S output	Present; includes a new setting for compatibility with third-party DACs
Output switching	Optimised
Power button	Power-on via single press or long press
Screen control	Screen power-on and power-off function adjusted for remote control and main button
USB output	The device automatically pauses playback if the USB DAC is disconnected

Technical Details

The listed specifications help compare the product’s configuration, compatibility and performance.

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Frequently Asked Questions

What type of product is the ONIX Zenith XST20?

It is an SACD transport, namely a device dedicated to reading CDs, SACDs and MQA and sending the digital signal to an external device.

Which discs does the ONIX XST20 read?

The product is indicated for CD, SACD and MQA playback and uses a Sanyo HD870 CD mechanism.

Which digital outputs are available?

I2S over HDMI, BNC, AES/EBU over XLR, coaxial, Toslink optical and USB-A are available.

What is the purpose of the new I2S setting in firmware V2.0?

It serves to increase compatibility with some third-party DACs. The firmware also includes a configurable option for the 5 V voltage of the I2S Mute pin; the setting is indicated, among other cases, for some older Topping DACs.

What happens if the USB DAC is disconnected during playback?

When the USB output is used, the XST20 automatically pauses playback if the USB DAC is disconnected.