Pass Labs - HPA-1c Headphone Amplifier

Introducing the HPA-1c — A Classic, Refined

Building on the legacy of the award-winning HPA-1, the new HPA-1c raises the bar in headphone amplification. While the core amplifier circuit remains true to its original, highly regarded design, we've taken the opportunity to refine and enhance its performance.

Driven by the need to replace end-of-life components, the HPA-1c features an upgraded power supply and improved circuit board grounding. These updates deliver a cleaner, more stable power foundation—resulting in lower noise, tighter regulation, and a blacker background.

We've also added local regulation to the servo circuitry and achieved approximately a 10 dB improvement in overall noise performance. The result? Greater low-level detail and improved clarity, especially with high-sensitivity headphones where it matters most.

In addition to its excellence as a headphone amplifier, the HPA-1c continues to function as a high-performance line-level preamplifier. With its discrete, class A design and robust output stage, it's equally at home at the heart of a reference speaker system.

Headphone Output:
The HPA-1 delivers up to 2 watts into 32 ohms, with a low output impedance of 2 Ohms.
It's designed to drive most dynamic and planar magnetic headphones with authority, including low-impedance and high-sensitivity models.

Preamplifier Output:
The preamp section is capable of driving a typical power amplifier load (10kΩ or higher) with very low output impedance.

“An updated version of the award-winning HPA-1. The “c” version features an upgraded power supply and improved grounding, leading to lower noise and greater clarity, especially with high-sensitivity headphones.” positive-feedback.com Review – Juan C. Ayllon