XDUOO TA-68 Fully Balanced Tube Headphone Amplifier & Preamplifier

XDUOO TA-68 Fully Balanced Tube Headphone Amplifier

The XDUOO TA-68 is a flagship fully-balanced desktop tube headphone amplifier and preamplifier built around tube rectification, 12AU7 preamplification, and 6C19 current amplification. Every stage of the signal path is processed by vacuum tubes, delivering the rich, organic harmonics and emotional engagement that only a pure tube topology can provide, with support for headphones from 60 to 600 ohms.

Fully Balanced Signal Path

The TA-68 uses separate tube circuits for the left and right channels from input to output. This fully-balanced architecture delivers stronger channel separation, clearer spatial placement, and a quieter background when used with compatible balanced sources and headphones.

Tube Rectifier Architecture

Two 5U4G tubes provide high-voltage rectification with independent anode voltage for the left- and right-channel circuits. This tube-based power stage contributes to the amplifier’s smooth, full-bodied tonal character.

12AU7 Tube Preamplification

Two matched and screened 12AU7 dual-triode tubes handle voltage amplification, giving the TA-68 a warm, rounded presentation while retaining detail and clarity during extended listening sessions.

6C19 Tube Buffer Stage

Each channel uses two matched 6C19 power tubes for current amplification. This four-tube buffer stage supplies the drive required for headphones with impedances from 60 to 600 ohms.

Capacitor-Coupled Output

A classic capacitor-coupled output topology preserves the tonal qualities of the tube circuit while isolating headphones from direct current at the output stage.

Premium Audio Capacitors

Vishay audiophile capacitors are used for signal coupling, while audio-specific Nichicon capacitors handle power-supply filtering. Together they support a smooth tonal foundation, controlled treble, and consistent signal transfer throughout the amplifier.

Dual Isolated Power Transformers

Two low-noise, low-flux-leakage EI transformers provide separate power feeds for the left and right channels. Isolating the channel supplies reduces inter-channel crosstalk and supports measured channel separation of up to 80 dB in balanced operation.

Independent Channel Controls & Two-Level Gain

Separate volume knobs allow the left and right channels to be adjusted independently, making it easy to correct channel imbalance, compensate for recording differences, or fine-tune image placement. A two-level adjustable gain mode helps pair the amplifier with different headphone sensitivities.

Versatile Inputs & Three Headphone Outputs

The rear panel includes stereo XLR and 4.4mm balanced inputs plus a stereo RCA input for single-ended sources, with a front-panel selector for balanced or line-level modes. The front panel provides 4-pin XLR balanced, 4.4mm balanced, and 6.35mm single-ended headphone outputs, accommodating full-size headphones without adapters.

Relay Protection & Delayed Startup

A relay-based protection circuit applies a 45-second warm-up delay when the amplifier is powered on, letting the tubes stabilize before outputs engage while reducing power-on/off thumps and limiting inrush current.

Swappable Tubes & Durable Chassis

All tubes are socket-mounted, allowing compatible replacements from different manufacturers to tune the amplifier’s tonal balance while preserving the original circuit design. The aluminum alloy enclosure with sandblasted front panel and ventilated protective tube cage shields the circuitry from electromagnetic interference.

Specifications

• Model: TA-68
• Product Type: Balanced tube headphone amplifier & preamplifier
• Power Supply: AC 100–120V or AC 220–240V
• Rectifier Tubes: Two 5U4G
• Preamplifier Tubes: Two 12AU7
• Buffer Tubes: Four 6C19
• Balanced Inputs: Stereo XLR and 4.4mm
• Single-Ended Input: Stereo RCA
• Balanced Headphone Outputs: 4-pin XLR and 4.4mm
• Single-Ended Headphone Output: 6.35mm
• Balanced Output Power: 120mW (75Ω) / 160mW (150Ω) / 200mW (250Ω) / 330mW (300Ω) / 240mW (600Ω)
• Single-Ended Output Power: 60mW (75Ω) / 100mW (150Ω) / 130mW (250Ω) / 210mW (300Ω) / 160mW (600Ω)
• Gain: 24dB balanced / 18dB single-ended
• Frequency Response: 10Hz–80kHz (±0.5dB)
• Channel Separation: 80dB balanced / 71dB single-ended
• Signal-to-Noise Ratio: 116dB balanced / 110dB single-ended (A-weighted)
• THD: 0.1% (1kHz @ 300Ω)
• Recommended Headphone Impedance: 60–600Ω
• Startup Delay: 45 seconds
• Dimensions (W × D × H): 33 × 30 × 18.5 cm
• Weight: 11.0 kg

What's Included

• TA-68 balanced tube headphone amplifier
• Two 5U4G rectifier tubes
• Two 12AU7 preamplifier tubes
• Four 6C19 buffer tubes
• Protective tube cage
• Power cable