1. Introduction
The TOPPING A90 Discrete is a high-performance, fully discrete balanced headphone amplifier and preamplifier designed for audiophiles. It features a powerful 9800mWx2 NFCA output, supporting various headphone connections including 4-pin XLR, 4.4mm balanced, 6.35mm single-ended, and 3.5mm single-ended. This device offers precise volume control, multiple gain settings, and advanced features like a ground loop noise terminator and 12V trigger interface for seamless integration into your audio system.
Image 1.1: TOPPING A90 Discrete in silver and black.
2. Package Contents
Please check that all the following items are included in your package:
- 1 x TOPPING A90 Discrete Unit
- 1 x Remote Control
- 1 x AC Power Cable
- 1 x 6.35mm to 3.5mm Adapter
- 1 x User Manual
- 1 x Warranty Card
3. Product Features
- Precise Volume Control: The A90 Discrete features an R2R volume control system, constructed with relays and resistor networks. This design ensures accurate volume adjustment, long lifespan, perfect channel balance, and remote control capability for an enhanced listening experience.
- Wide Compatibility: Supports a variety of headphones with 4-pin XLR balanced, 4.4mm balanced, 6.35mm single-ended, and 3.5mm single-ended jacks, offering flexibility for diverse audio setups.
- Multiple Gain Options: Equipped with low and high gain settings, the A90 Discrete efficiently drives both sensitive IEMs and full-size over-ear headphones. Its ultra-low noise level of 0.2uVrms prevents noise even with highly sensitive IEMs.
- Ground Loop Noise Elimination: Includes a GND/LIFT switch to resolve potential ground loop noise issues that can occur when connecting multiple devices. Switching to LIFT mode helps eliminate ground loop noise.
- 12V Trigger Interface: Features a 12V trigger interface for active or passive control. Use a 3.5mm to 3.5mm cable to synchronize power on/off with other devices equipped with a 12V trigger interface, simplifying operation.
- Fully Discrete NFCA Modules: Utilizes fully discrete NFCA (Nested Feedback Composite Amplifier) modules for superior audio performance.
- High Output Power: Delivers 9800mW x 2 output power, capable of driving demanding headphones with ease.
Image 3.1: Key features of the A90 Discrete.
Image 3.2: Headphone output options and gain settings.
Image 3.3: Internal components and performance characteristics.
4. Interface Diagram
Familiarize yourself with the front and rear panel interfaces of the A90 Discrete.
Image 4.1: Front and Rear Panel Layout.
Front Panel:
- Output Channel Indicator
- Remote Control Receiver
- Power Indicator
- Input Channel Indicator
- Volume Display
- 4-PIN XLR Headphone Output Jack
- 4.4mm Balanced Headphone Output Jack
- 6.35mm Headphone Output Jack
- Volume Knob / Multi-function Button
Rear Panel:
- Firmware Upgrade Interface
- Extender Input Interface (for TOPPING Ext90)
- Balanced XLR Input
- Single-ended RCA Input
- Single-ended RCA Output
- Balanced XLR Output
- Trigger Interface (12V)
- Ground Lift Switch (GND/LIFT)
- Power Input (AC 100-240V 50Hz/60Hz)
- Power Switch
5. Setup Guide
5.1 Initial Connection
- Power Connection: Connect the supplied AC power cable to the "Power Input" (2-9) on the rear panel and then to a suitable power outlet.
- Input Source: Connect your audio source (e.g., DAC, CD player) to the A90 Discrete using either the "Balanced XLR Input" (2-3) or "Single-ended RCA Input" (2-4).
- Output to Headphones: Connect your headphones to the appropriate output jack on the front panel: "4-PIN XLR Headphone Output Jack" (1-6), "4.4mm Balanced Headphone Output Jack" (1-7), or "6.35mm Headphone Output Jack" (1-8). Use the provided 6.35mm to 3.5mm adapter if your headphones have a 3.5mm plug.
- Output to Power Amplifier/Active Speakers (Preamplifier Mode): If using the A90 Discrete as a preamplifier, connect its "Single-ended RCA Output" (2-5) or "Balanced XLR Output" (2-6) to your power amplifier or active speakers.
- Optional Extender Connection: If using the TOPPING Ext90, connect it to the "Extender Input Interface" (2-2) to expand input options.
- Optional 12V Trigger: Connect a 3.5mm to 3.5mm cable between the "Trigger Interface" (2-7) and another device with a 12V trigger to synchronize power.
5.2 Power On/Off
- Flip the "Power Switch" (2-10) on the rear panel to turn the unit on or off.
- The "Power Indicator" (1-3) on the front panel will illuminate when the unit is powered on.
6. Operation
6.1 Volume Control
- Rotate the "Volume Knob / Multi-function Button" (1-9) on the front panel to adjust the volume.
- The current volume level is displayed on the "Volume Display" (1-5).
- The remote control can also be used for volume adjustment.
6.2 Input Selection
- Press the "Volume Knob / Multi-function Button" (1-9) to cycle through available input sources.
- The "Input Channel Indicator" (1-4) will show the currently selected input.
- The remote control can also be used to select inputs.
6.3 Gain Settings
- The A90 Discrete offers two gain settings: Low Gain and High Gain.
- These settings can be adjusted via the remote control or a specific function on the multi-function button (refer to the detailed manual for specific button presses).
- Select Low Gain for sensitive headphones (IEMs) to prevent excessive volume and noise.
- Select High Gain for less sensitive, full-size headphones that require more power.
6.4 Headphone Output vs. Preamplifier Output
- The A90 Discrete can function as both a headphone amplifier and a preamplifier.
- When headphones are connected, the unit operates as a headphone amplifier.
- When no headphones are connected, the unit can function as a preamplifier, sending the signal to a power amplifier or active speakers via the rear panel outputs.
- The device remembers individual volume settings for headphone and preamp modes, enhancing safety for sensitive IEMs.
7. Maintenance
- Keep the device clean by wiping it with a soft, dry cloth. Avoid using abrasive cleaners or solvents.
- Ensure proper ventilation around the unit to prevent overheating.
- Avoid exposing the device to moisture, extreme temperatures, or direct sunlight.
- Do not attempt to open the casing or modify the device, as this will void the warranty and may cause damage.
8. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| No sound output. |
|
|
| Humming or buzzing noise (ground loop). | Ground loop interference from connected devices. |
|
| Remote control not working. |
|
|
| Unit does not power on. |
|
|
If the problem persists after trying these solutions, please contact customer support.
9. Specifications
| Feature | Detail |
|---|---|
| Model | A90 Discrete |
| Brand | TOPPING |
| Channels | 2 |
| Output Power | 9800mW x 2 |
| Input Interfaces | XLR, RCA, EXT (for TOPPING Ext90) |
| Headphone Output Interfaces | 4-pin XLR, 4.4mm Balanced, 6.35mm Single-ended, 3.5mm Single-ended (via adapter) |
| Preamplifier Output Interfaces | XLR, RCA |
| Gain Settings | Low Gain, High Gain |
| Noise Level | 0.2uVrms (Ultra-low) |
| Dimensions | 16 x 22.2 x 4.5 cm |
| Power Input | AC 100-240V 50Hz/60Hz |
10. Warranty Information
The TOPPING A90 Discrete comes with a warranty card included in the package. Please refer to the warranty card for specific terms and conditions, including the warranty period and coverage details. Keep your proof of purchase for warranty claims.
Note: The warranty may be voided if the device is opened, modified, or damaged due to improper use.
11. Customer Support
For technical assistance, troubleshooting, or warranty inquiries, please contact the seller or TOPPING customer support.
- Seller: AOSHIDA (as indicated by the brand store link in the product data).
- Online Support: If you encounter any issues during purchase or use, please contact us directly. We are available online to assist you.
- Shipping Issues: If there are any problems with the package, please contact Amazon Customer Service first, then inform us.
For more information, you may visit the AOSHIDA Store on Amazon.
