Review on Douk Audio U3 Mini Class A Headphone Amplifier - HiFi Desktop Home Stereo Amp (DC5V) by Melissa Marie

TL:DR - I don't know if anything can top this $30 for 200 ohm+ headphone performance. Also makes a very good little portable setup as it can run on battery power. A clean power supply makes a noticeable difference. The USB 3 ports on the front of my PC are adequate and make no noise, although your mileage may vary. I have four other amps: Magnius, Magni, JDS Labs Element 2 and THX 789 (Asgard 3 otw too). This little thing beats Magni when it comes to soundstage. One caveat is that I replaced the TI-553NE with a JRC-4558D from the BoJack op amp kit I bought here for $15. Aside from being able to still hear music and volume control balance issues at "zero", I give this amp a 4/5 for sound quality with "JRC-4558D" (3.5/5 headroom ) and 5/5 for everything else. The swap removed the "Whizzoopp" start-up noise that capacitors make at start-up as they fill up, and reduced crosstalk when the volume knob was at "zero". The board is laid out nicely and confirms the fact that component spacing results in a SIGNIFICANT reduction in noise/crosstalk. I plan to make a video about it and try to reproduce the circuit in SPICE or a similar program to see what areas can be improved. The simplest and most obvious upgrades seem to be capacitors, grounding, op-amps, and component spacing. (Hardware used) DAC: Schiit Modius, Fiio BTR3K, iPhone 11 Pro, i5-10600k Headphones: HD600, HD660s, HD280 Pro, HD650