HPA4 - "Class A Recommended" Headphone Amplifier
"With the hard-to-drive HiFiMan Susvara headphones, the HPA4 showed each instrument in dramatic bas-relief. It accomplished this by presenting cleaner, better-articulated bass and manufacturing a sharper midrange focus than I had experienced previously with either my solid state reference, the Pass Labs HPA-1, or the tubed Linear Tube Audio Z10e.”
- Herb Reichert
"The LA4 preamplifier was the widest-bandwidth, widest-dynamic-range, lowest-noise, lowest-distortion preamplifier I had encountered at that time ... to those virtues, the HPA4 adds equally superb balanced and single-ended headphone outputs."
- John Atkinson
