All-aluminum shell, with gold-plated RCA interface, exquisite appearance, classic luxury. Bluetooth 5.0 - Support U disk input - RCA audio - Multiple inputs - HiFi tube preamp headphone amplifier. High fidelity tube preamp HiFi headphone amplifier - Support U disk input, support APE, FLAC, WAV and other lossless playing - Can be used as a high-fidelity lossless music player - Rich audio input interface, freely switch audio inputs - Adjust treble and bass at you will. USB: For U disk input - Input: Audio input (Connect to PC, cellphone, CD, players and the like) - ANT: Bluetooth signal input - Audio output: Connect to power amp or active speakers - POWER: Switch. Product model: A9 - Working voltage: DC 12V - Frequency response range: 20Hz-20KHz (±3dB) - Audio input: Bluetooth 5.0/RCA/U disk (U disk is not included) - Audio output: RCA/3.5mm headphone jack - Signal to noise ratio: =110dB (when RCA input) - Distortion: 0.05% - U Disk: 32GB - U Disk: MP3/WMA/APE/FLAC/WAV, etc.- Maximum output power of earphone: 100mW 32? Load - Input sensitivity: 0.775V - RCA output level: 1.4Vrms - Treble, mid-tone, bass gain: ±6dB - Product size: 13143 CM - Machine weight: 0.42kg.