The Topping A90 Discrete is a headphone amplifier with 4 built-in NFCA-Discrete modules, each using 39 transistors. The Topping A90 Discrete Amplifier features a front panel volume amplifier, two balanced headphone jacks, and a 6.3 mm headphone jack. The Topping A90 Discrete has 9.8 W of output power per channel and is considered one of the best measuring amplifiers and preamplifiers. The Topping A90 Discrete adds a layer of lightness and refinement to your music.