FiiO K7 Full Balanced HiFi DAC Headphone Amplifier AK4493S*2, XMOS XU208 PCM384kHz DSD256,USB/Optical/Coaxial/RCA Inputs, 6.35mm/4.4mm Output The most competitive and cost-effective desktop balanced DAC/Amp within the 300-USD range; Adopts the six-stage audio circuit as in FiiO’s high-end devices, and features 2 AMK’s latest AK4493SEQ DACs and dual THX AAA 788+ amps; Adopts the six-stage audio circuit as in FiiO’s high-end devices, and features 2 AMK’s latest AK4493SEQ DACs and dual THX AAA 788+ amps; Comes with versatile functions as well as robust output power- 1% THD+N under BAL output, 2000mW stable output power, which can drive most headphones, including full-size headphones; Supports input selections, 2 gain levels and 3 output levels, and features RGB indicator lights that can display the working state and differentiate sampling rates. K7 FAQ How to use the K7 as a USB DAC for mobile phones? K7 does not have a battery, it is powered by a built-in linear power supply, you can purchase an OTG cable to connect to an Android phone, an iPhone or a player.Android phone. K7 input setting: K7 [INPUT] switch to USB gear K7 output setting: switch to the corresponding output port according to the interface used, switch to [PO] on the front panel headphone out, switch to [PRE] or [LO] on the rear panel line-out. Connect the phone and K7 via USB C to USB B data cable (such as FiiO LD-TC1) [Note] If there is no sound after you connect, you need to pay attention to the following points: Mobile phone playback software settings, if there is a USB output setting that needs to be turned on, some devices only have sound when the USB output is turned off; Confirm that USB debugging is enabled in the developer mode of the mobile phone; You need to turn on USB debugging on the mobile phone, turn on "Developer Options", and then turn on the "USB debugging" or "OTG" function; Confirm that the adapter cable supports the OTG function, and whether the direction of the cable is reversed; IPhone/iPad You need to purchase a Lightning to USB B data cable which supports OTG function(e.g. FiiO LD-LT1) to connect K7 and iPhone/iPad/iPod, and you can enjoy high-quality music by playing songs. Balanced decoding and amplification The K7 has a six-stage audio circuit with truly balanced analog and digital sections – which helps to reduce crosstalk and reproduce music to a great extent, allowing you to better enjoy the purity of your music. THX AAA 788+ amplifier Using the same THX AAA 788+ amplifiers as the K9 Pro, the K7 is capable of outputting 560mW into a 300Ω load at 1% distortion, and 2000mW into a 32Ω load at 1% distortion. Dual AK4493SEQ The left and right channels are each equipped with an efficient high-performance AK4493SEQ. With this DAC’s pleasant timbre, its rich and delicate overall sound will let you rediscover your music all over again. XMOS XUF208 The XMOS XUF208 decoder chip uses dual clock management to handle various music formats with ease, allowing you to easily listen to many audio formats. Low-noise power supply The K7 features a power design consisting of multiple independent stages, with a voltage of each stage being regulated by low-noise LDOs. Feeding this power design is an external 12V switching power supply Variety of inputs and outputs The K7 contains USB, optical, coaxial, and RCA inputs. Outputs are 6.35mm single-ended and 4.4mm balanced for pleasant listening no matter the headphones. Two gain levels The high and low hardware gain levels allow you to easily adjust the K7 to handle headphones of various impedances and sensitivities for a rich and consistent listening experience.