Pass Labs

Nelson Pass founded Pass laboratories, Inc in 1991 after leaving “Threshold”, a company which Nelson and his co-founder founded and worked for 17 years. Nelson and Mike Burley started designing prototypes of single-ended class A amplifiers from their home. Their first amplifier was single-ended, class A design: the Aleph 0, a mono-block outputting 70 watts into 8 ohms. They made a complementary preamp called Aleph P to go with it.

Pass believes that a love for music is a must to design and product amplifiers and he draws inspiration from a long list of people. The company believes that a combination of subjective listening experience and objective measurements, both are important to do their job. They focus mainly on class A amplifiers, reasoning that it makes achieving good sound easier than other types of amplifiers. Another of their important beliefs is that the amplifier must sound good at a lower wattage, not only at higher wattage, saying that most people don’t realise how little power they are listening to.

Pass Labs continued in making new designs, releasing a new Aleph design in 1994 with a simplified two stage gain circuit from a three gain circuit. In 1997 they released their first phono stage and then the D1 DAC. They released their widely popular XA amplifiers in 2002 combining the X and Aleph topologies.

Pass Labs’s class A amplifiers and preamplifiers are till now some of the best in the world and a first choice among many audiophiles.

Pass Labs Headphone Amps

Pass Labs



United States