1) volume which connect the computer for the first time when the default volume is small but you have to turn the volume potentiometer counterclockwise to minimum so as to avoid the volume is too big damage to the headphones or amplifiers need to adjust in the synthesizer. Method of use like computer sound card you should understand if you feel the volume is small can use the USB an ASIO driver the volume is larger than the normal 50%. 2) player software and sound source the effect of different software and audio out is different it is recommended to use cool dog music download and play music APE format if you use ordinary MP3 format file its music background is not clean a bottom this is the sound source of the problem not a sound card problem change the APE format there is no this problem. 3) driver 2704 USB DAC system used to own a USB AUDIO driver do not need to install even directly on them.If they think is a computer expert can provide USB an ASIO driver the driver is very good can improve the sound quality but are relatively tedious install and use every player software to set up is very troublesome if not set the sound card is not a sound I provide a cool dog music setting method the other player software need oneself fumble does not provide any Suggestions please don't ask don't can be in Baidu search because each taught it again need to 24 hours to do my computer teacher also not necessarily can teach please understanding. If other USB an ASIO driver the volume to 50% larger than system comes with the driver general use 2/5 volume can meet the needs of the headphones. This circuit board advocate chip adopts the BB company "HIFI PCM2704 USB decoding chip after our company training effect than the common USB decoding chips on the market effect is good power using USB interface on the power through special ELNA audio capacitor filter give ear and DAC power supply. Because is external sound card thus bypassing the interference inside the case serious electromagnetic waves allowing quality to purify high signal-to-noise ratio plus TPA152HIFI headset chip can drive 16-150 the most common HIFI headphones can Bi CD quality. Excellent effect of computer with sound card You may have on the sampling rate is not very understanding now digital products and computer can access data namely the work while you read is digital signal and audio output analog signals are needed to facilitate the amplifier to drive the horn ear to hear and the current MP3 WAV format such as music is compressed the sound quality is bad to have good quality music need to download the APE lossless music and APE is the source of the music CDS the CD disc number format is 16 bit 44.1 k PCM2704 USB DAC is read the USB port of the digital signal through internal D/A conversion recreate the voice of the CDS so its quality than the on-board computer AC97 many sound CARDS can Bi CD quality. The PCM2704 USB DAC decoder amp in the process of using the metaphone hissing sound strange problems may be there is something wrong with the computer using the player the plugin is damaged and the sound quality even cause metaphone hissing sound strange problems such as damage to the player play whether it is a built-in sound card or external sound card will come out the strange noise this is a problem player not a sound card problem it is recommended to use WINDOWS's own player.