thumb|Aleph 3 Amplifier
Pass Labs (formally Pass Laboratories, Inc.) is an American manufacturer of high-end audio equipment based in Auburn, California. The company was founded in 1991 by audio designer Nelson Pass and produces solid-state power amplifiers, preamplifiers, headphone amplifiers and related components aimed at the audiophile market.
History
Nelson Pass founded Pass Labs in 1991 in northern California, initially operating from his home workshop.
By the late 1990s Pass Labs had introduced the X series of amplifiers marketed under the name "SuperSymmetry". These current domain amplifiers are only suitable for use with certain types of speakers. With respect to the Aleph amplifier line, First Watt has announced plans for the Aleph J, a revision of the famous Pass Labs Aleph 3/Volksamp Aleph 30 wherein a new JFET input stage is to be added.
X, XA and XS series
Current Pass Labs "X" series amplifiers use a distortion canceling balanced audio signal circuit..
Preamplifiers, headphone amplifiers and loudspeakers
Pass Labs manufactures line-level preamplifiers and phono stages under the XP and XS designations, which use solid-state circuitry and are positioned for use with the company's power amplifiers and other high-end systems.
In 2015, Pass Labs introduced the HPA-1, a Class A headphone amplifier that also functions as a compact line preamplifier. The HPA-1 uses a discrete MOSFET output stage and is designed to drive a wide range of headphone loads.