• Compact Bluetooth headphone amplifier with powerful technology to deliver high-quality wireless sound to your headphones
• Supports high-quality LDAC, aptX and AAC audio codecs
• Output mode switch allows selection of output impedance suitable for dynamic or balanced armature drivers
• Built-in microphone allows you to take calls from a paired smartphone
• Aluminum housing reduces unwanted resonance
• 3.5 mm (1/8") stereo output jack
• Up to 8 hours of continuous use
• Includes belt clip and 30 cm (1") USB charging cable

Features:

• 32-step multilevel digital volume selection
• LED status indicators display the currently connected codec, the pairing and charging status, and the remaining battery level
• ESS Technology ES9118 HiFi System-On-Chip (SoC) ensures faithful reproduction of the original sound
• Jitter is suppressed by controlling the clock from the wirelessly transmitted input signal side, resulting in crisp, clear audio quality with high transparency
• 50 mW + 50 mW high-output amplifier drives connected headphones to perform at their maximum potential

The AT-PHA55BT wireless headphone amplifier is a compact but powerful tool that will help you get the most out of your headphones – wherever you go. Utilizing Bluetooth® wireless technology and supporting LDAC, aptX, AAC and SBC audio codecs, the amplifier processes the digital transmission from your Bluetooth device and faithfully converts it to an analog signal via an ESS Technology ES9118 HiFi System-On-Chip (SoC). Offering up to eight hours of continuous use and a max output level of 50 mW + 50 mW, the AT-PHA55BT has the power to drive your headphones to their full potential.

Additionally, the amplifier features an output mode switch that allows you to select between two output impedance levels – one suitable for headphones with dynamic drivers, the other for headphones with balanced armature drivers – ensuring you get the best sound possible. The amplifier is designed to suppress wireless jitter and reduce acoustic resonance, and allows for fine audio tuning through its 32-step multilevel digital volume control.

The AT-PHA55BT is equipped with LED indicators that display the battery level, pairing and charging status, and the codec currently in use. The amplifier also includes a microphone so you can take calls from a paired smartphone, and comes with a belt clip and a 30 cm (1') USB charging cable.

*The Bluetooth® word mark and logos are owned by Bluetooth SIG, Inc. and any use of such marks by Audio-Technica Corporation is under license. Other trademarks and trade names are those of their respective owners.

Specifications:
Maximum Output Level:
50 mW + 50 mW (at 16 ohms, T.H.D. 10%)
25 mW + 25 mW (at 32 ohms, T.H.D. 10%)
2.5 mW + 2.5 mW (at 300 ohms, T.H.D. 10%)
Output Connector: 3.5 mm (1/8") gold-plated stereo mini jack
Battery: DC3.7 V lithium polymer rechargeable battery
Battery Life:
Max. 8 hours continuous use (100 hours standby)
Charging Time: Approx. 3 hours (for 0-100% charge)
Operating Temperature: 41 – 104° F (5° – 40° C)
Dimensions (excluding protrusions): 79 mm (3.1") H × 32 mm (1.3") W × 11 mm (0.4") D
Weight: 28 g (1 oz)
Accessories Included: 30 cm (1') USB charging cable, belt clip
Type (Microphone): Condenser
Sensitivity (Microphone): -36 dB (1V/Pa at 1 kHz)
Frequency Response (Microphone): 50 – 8,000 Hz
Polar Pattern (Microphone): Omnidirectional
Input jack: Micro USB Type B
Communication System: Bluetooth Version 4.2
Output: Bluetooth Specification Power Class 2
Maximum Communication Range: Line of sight - approx. 10 m (33')
Compatible Bluetooth Profiles: A2DP, AVRCP, HFP, HSP
Support Codec: LDAC, aptX, AAC, SBC