Why I chose the Aikido as the basis for my Headphone Amplifier:
High Impedance Headphone Amplifier design by John Broskie
Low Impedance Headphone Amplifier design by John Broskie
Power supply design by John Broskie
The Printed Circuit Board by John Broskie (Quality is Amazing - Highly recommended)
First Build: High Impedance with Output Transformers for Low Impedance Headphones
Second Build: Low Impedance - capacitor coupled no output transformers