Improved Compatibility: With a 3.5mm RCA AUX/stereo input and a 3.5mm/6.35mm headphone jack output, the U3 PRO is compatible with a wide range of audio sources, including MP3 players, iPods, smartphones, tablets, computers, and CD players, etc. Its output can connect to various headphones, providing a versatile listening experience with support for most headphone models. Built-in Voltage Amplifier Circuit: By adopting an innovative circuit design with a built-in voltage amplifier circuit, the amplifier circuit can always operate at a high voltage of ±14V even when powered solely by DC 5V, and the noise floor is excellent. With a wide frequency response extension, excellent transient response, excellent purity and transparency, and good dynamic range. Exceptional output power: for a total power of up to 1500mW into a 32Ω load, the U3 PRO can easily drive headphones with any impedance, low or high (18-600Ω). Operating in Class A, with ultra-low distortion, the sound is warm and delicate, full and smooth with high quality Exceptional sound. Classic OP+BUF Architecture: The U3 PRO adopts OP42 and BUF634, with a pure DC amplification circuit. Plug-in op-amp socket design; the OP42 can be replaced with OP17, AD797, AD843, AD847, and OPA627, convenient for upgrading different op-amps and bringing a lot of DIY fun and playability for audiophiles. Highly Cost-Effective: Mini size with exquisite appearance, a great surprise for all audiophiles, easily drives most headphones on the market, providing greater power, better soundstage and detail, very suitable for use in desktop audio systems. the house.