PJ. MIAOLAI M7 Bluetooth tube front amplifier 6K4 tube HIFI preamplifier can be upgraded to 6J1 GE5654

Product Description:-M7 Feaver electron tube,audio signal input port can connect computer,CD lossless music player,mobile phone,tablet PC,laptop. The audio output port can connect various digital amplifier,active multi-media speakers and audio devices.- Full aluminum shell,M7 High and low tone adjustment-M7 audio input and output port uses thick gold plating,lossless signal transmission.-6J1 electron tube-M7 BTM625 bluetooth audio module,CSRA64215 chip,supporting A2DP,AVRCP,HFP,TWS,AAC,I2S,APTX,APTX-LL. 4M SPI FLASH storage chip. External high gain detachable antenna,stable signal transmission.-2pcs high quality relay & crystal oscillator,switch-on protection function.-ESS9023 bluetooth decoding,112dB dynamic range,24 bit stereo audio degital analog convert chip DAC,SABRE digital analog conversion technology.Specification:- Audio input port:RCA input x 1 group- 3.5 stereo input x 1 group- Wireless bluetooth input x 1 group- Audio output port:RCA output x 1 group- Power supply in