Zhaolu made quite splash here in the mid 2000s with their DAC/Preamp/Headphone amplifiers and you can search to find out more. Still a superb sounding unit and works flawlessly. Features include:

• Fully discrete, powerful Class A headphone amp module upgrade.
• Analog Devices 1852 DAC chip
• 1 Analog input
• 1 fixed level analog output from the DAC
• 1 variable preamp output for connection to a speaker power amplifier and to us the unit as a Class A preamp
• 1 balanced XLR output
• Toslink optical input
• Coaxial digital input
• Opamps can be rolled in the analog output stage (comes with Burr Brown OPA2604's)

Comes with:

• Original box and packing
• Toslink cable
• Power cord

Shipping is included in the price to the continental US.

Thanks!