FIIO K7 Compact Desktop Headphone Amplifier with USB Dual [Fiio] Built-in DAC, Configuration, THX-AAA 788+

The K7 features a dual configuration of Asahi Kasei Electronics' latest DAC chip, the "AK4493SEQ": The K7 uses a dual configuration, with one "AK4493SEQ" chip for each of the left and right channels. This is the latest DAC chip from Asahi Kasei Electronics (AKM), a redesign of its predecessor, the "AK4493EQ," using current high-quality sound technology. Designed based on advanced VELVET SOUND technology, the "AK4493SEQ" effectively suppresses power consumption through impedance optimization while pursuing rich information, a sense of speed in sound, and realistic spatial expression. Furthermore, by revising the noise design, the perceived noise level has been significantly improved beyond the catalog specifications. The specifications show an S/N ratio of up to 128dB and a THD+N of -115dB, achieving excellent analog characteristics. Fully balanced design from DAC to headphone amplifier: The K7's audio circuit is based on the same architecture as the top-of-the-line K9 Pro ESS model, and is a fully balanced circuit consisting of six blocks: "DAC, low-pass filter, volume control, buffer amplifier, preamplifier, and headphone amplifier." By thoroughly applying differential signal input to each block separated for the left and right channels, mutual interference that negatively affects sound quality is eliminated to the greatest extent possible, enabling higher-level music reproduction that is more faithful to the signal. The K7 features two "THX-AAA 788+" headphone amplifier circuits jointly developed by FiiO and THX: The K7 is equipped with the same "THX-AAA 788+" amplifier circuit as the K9 Pro ESS, FiiO's top-of-the-line desktop headphone amplifier. This circuit is an amplifier circuit jointly developed by FiiO and THX based on the "THX-AAA 788" circuit to provide ideal detail and dynamics for all headphone playback, from high efficiency to low efficiency. The K7 thoroughly implements a fully balanced configuration, with one amplifier per left and one per right channel, for a total of two amplifiers, achieving high output of up to 2000mW at a 32Ω load and up to 560mW at a 300Ω load. The K7 uses the XMOS "XUF208" as its USB decoding chip. This chip enables decoding of PCM up to 384kHz/32bit, DSD up to DSD256 (Native), and DSD128 (DoP). Dual clock management technology ensures that the optimal clock is always selected for the input source, resulting in high-quality D/A conversion. Clean, independent power supply circuit design: To suppress power supply noise that can negatively affect sound quality, the K7 features a power supply circuit design that provides independent power to each block of the circuit. Power supplied from an external 12V switching power supply is kept clean by low-noise LDOs responsible for each block, and is then supplied to the components in the appropriate amounts. ADC Volume Control Function for Precise Volume Adjustment: The K7 features an ADC volume control function for volume adjustment. Unlike analog volume control methods that directly manipulate a variable resistor through which the music signal is passed, this method controls the volume IC based on the value obtained by A/D conversion of the amount of rotation of the volume knob. This eliminates the problems of analog volume control, such as left/right volume differences and noise, while allowing for 112 steps of fine volume adjustment. Equipped with a two-stage hardware gain adjustment function: The K7's hardware gain can be adjusted in two stages, High and Low, by operating the GAIN switch on the front of the unit. By adjusting the gain according to the efficiency of the connected headphones, you can always enjoy music at a comfortable volume level. Equipped with a variety of inputs and outputs, the K7 can be as the centerpiece of your audio system: The K7 supports digital inputs using USB, RCA coaxial, and optical terminals, analog inputs and outputs using RCA terminals, and single-ended output using a 6.35mm headphone jack and balanced output using a 4.4mm terminal. Beyond connecting to a PC, it can connect to various digital devices for high-quality balanced connections to enjoy music, and can be easily integrated into your existing audio system. The INPUT buttons on the front panel allow you to switch between inputs. Pressing a button illuminates a colorful indicator to show that the input has been switched. The OUTPUT switch allows you to switch between three output modes. This allows you to select the appropriate output mode for enjoying music with headphones, connecting to active speakers, or connecting to an external amplifier as a pure DAC. Featuring RGB indicator lights that blend functionality and design: The K7's RGB indicator lights have evolved further from the K5 Pro ESS, and can now display not only single colors but also mixed colors. The K7 glows uniquely and vividly in response to power on/off and input switching, making it a visually striking presence on your desk. Sophisticated and Simple Enclosure Design: The K7's enclosure is constructed from highly rigid aluminum alloy, with parts carefully processed and assembled using CNC machining. Its compact size—55mm in height and less than one-third the width of an A4 sheet of paper—allows for neat placement on a desk. Furthermore, its simple and modern design blends seamlessly into any interior. The K7 is a compact, desktop USB DAC/headphone amplifier the same size as the K5 Pro ESS, yet it features a dual configuration with AKM's latest DAC chip, the "AK4493SEQ," operating one per left and one per right channel. The audio circuitry shares the same fully balanced design as the top-of-the-line K9 Pro ESS. This latest model supports balanced headphone connections, a feature frequently requested by users. The headphone amplifier circuit also utilizes the "THX-AAA 788+" technology, shared with the K9 Pro ESS, allowing for accurate reproduction of musical details without loss of quality, while delivering an astonishing drive power of up to 2000mW from its compact chassis.