Pass Laboratories has introduced the Pass Labs HPA-1c, a refined successor to its award-winning HPA-1 headphone amplifier and line-level preamplifier. The Pass Labs HPA-1c keeps the original’s discrete, class A circuit topology intact, but replaces end-of-life components with an upgraded power supply and improved circuit board grounding for a cleaner, more stable foundation.
Pass Labs HPA-1c: an evolution, not a reinvention
Pass Labs designed the HPA-1c to honor the reputation of the original HPA-1 rather than replace its sound. The core amplifier circuit remains true to the highly regarded original design, while the power supply now draws up to 23 watts of current, up from 8 watts, leaving considerably more headroom for demanding headphones. Local regulation has also been added to the servo circuitry, delivering roughly a 10 dB improvement in overall noise performance for a blacker background and greater low-level detail.
Headphone amp and reference preamplifier in one chassis
As a headphone amplifier, the Pass Labs HPA-1c delivers up to 2 watts into 32 ohms with a low output impedance of 2 ohms, giving it the authority to drive most dynamic and planar magnetic headphones, including low-impedance and high-sensitivity models. The unit doubles as a high-performance line-level preamplifier: its discrete class A design and robust output stage can drive a typical power amplifier load of 10 kilohms or higher, making it equally at home at the heart of a full speaker system.
Refined power supply, quieter background
The improvements to the HPA-1c center on power delivery and grounding rather than a new circuit. Pass Labs states the redesigned power supply and grounding scheme were driven by the need to replace components approaching end of life, and the brand used the opportunity to also tighten regulation throughout the unit. The result, according to Pass Labs, is lower noise and improved clarity that is most noticeable with sensitive headphones, where amplifier noise floor matters most. The company previously brought similar power-supply refinements to its Pass Labs XS Preamplifier 2.
Built by a class A specialist
Pass Laboratories has built its reputation on discrete class A circuit design since the early 1990s, and that philosophy carries directly into the HPA-1c. Rather than chasing feature lists, the company positions the Pass Labs HPA-1c as a tool for listeners who want the amplifier itself to disappear: a quiet, neutral gain stage that lets headphones and downstream components do the work. That approach explains why the original HPA-1 kept its core topology for the HPA-1c rather than being redesigned from scratch.
Pricing and availability
The Pass Labs HPA-1c is listed at $4,045 through the brand’s US dealer network, including Pass Labs retailer Moon Audio. Availability outside the US should be confirmed with local Pass Labs distributors.
Key specifications
- Type: class A headphone amplifier and line-level preamplifier
- Gain: 8 dB
- Frequency response: 10Hz-100kHz (-1dB)
- Output power into 32 ohms: up to 2W
- Output power into 20 ohms: 3500mW
- Output power into 300 ohms: 200mW
- THD + Noise: <0.005 at 1V out
- Input impedance: 50k ohm
- Output impedance: <2 ohms
- Power consumption: 23W
- Dimensions (W x D x H): 11 x 13.5 x 4 in.
- Weight: 14 lbs
- Price: $4,045
