Pass Labs launch new XA Series Class-A power amplifier

XA25 stereo power amplifier.

Pass Labs will be showing off their brand-new XA25 Power Amplifier at AXPONA this week, and announced today that the company has started shipping the Class-A amps which have an MSRP of $4,900 USD ($6,500 CAN).

According to Nelson Pass, the brand new design embodies everything that traditional, and current designs feature, but with lower-power requirements, a more simple single-ended circuit with fewer parts, and gain stages in the signal path. This translates into lower voltages allowing for higher-bias current in gain devices to run more deeply into Class-A. From everything I know about amps, this means it should sound most excellent.

I have the Pass Labs X150.8 power amplifier, and XP-10 preamplifier in for review right now, and I can tell you without hyperbole that these are deeply impressive designs that create an emotional connection to the music. I’m looking forward to hearing this new model in Chicago, and applaud any manufacturer who is releasing more affordable products that draw on technology from their higher-priced offerings.

–Rafe Arnott

From the press release:

Auburn, CA, April 17, 2017 Pass Labs has started shipping their new XA25 Class A Power Amplifier, the most affordable power amplifier in their current line. With 2 x 25W at 8 ohms, 2 x 50W at 4 ohms and 2 x 100W Class A/AB at 2 ohms, and priced at $4,900, the XA25 is not meant as merely an “Entry-Level” model, but rather, a more affordable way for consumers to experience the Pass Labs line and all its renowned traditions of founder Nelson Pass’ comprehensive design, construction and performance.

In other words: A smaller, lighter and less expensive Pass Labs Class-A power amplifier.

To paraphrase the words of Nelson Pass when describing the new XA25 Power Amplifier: At Pass Labs, we build FET amplifiers with excessive output stages, huge heat sinks and massive power supplies. We use the highest quality components in simple linear topologies, assembled and tested with care and subtlety. They measure well, sound great, and are reliable. Twenty+ years of ongoing innovation have kept the X and XA amplifiers at the forefront of high-end audio.

The XA25 embodies all this and less. A smaller Class A stereo amplifier at a lower price, it takes advantage of the lower power requirements to have simpler single-ended circuitry and fewer parts in the signal path. This also allows elimination of degeneration, “that other negative feedback,” in all stages.

Newer power FET technology replaces banks of parallel small transistors with a single pair of industrial devices, each having a 700 watt/40 amp rating. With no current-hogging issues and a new constant-current bias circuit to compensate for temperature drift, they connect directly to the loudspeaker without ballast resistors for lowest possible distortion and highest damping factor. No degeneration also increases the efficiency and Class-A operating current, allowing greater Class-A operation into low impedance and reactive loads.

The simple front end circuit uses two pairs of NOS complementary FETs in common-source mode in a current feedback (CFA) configuration. The amplifier is direct coupled and has no DC servos or frequency compensation. Inputs from the preamplifier or DAC are RCA.

According to Nelson Pass: “As with all Pass amplifiers, the technology and construction are strictly in the service of the listening experience. The XA25 measures superbly, but its subjective qualities are most special. In an industry where products with great specs are often found to be dry and boring, this amplifier breathes new life into the music. It follows the philosophy of PL amplifier design – still greater performance with still simpler circuitry.”


Output power:

2x 25 Watts Class A @ 8 ohms
2x 50 Watts Class A @ 4 ohms
2x 100 Watts Class A/AB @ 2 ohms
Distortion: 0.1% @ 25 Watts, 8 ohms, 1 KHz, 0.1% @ 50 Watts, 4 ohms, 1 KHz
Freq. Response: DC to 3dB @ 200 KHz
Gain: 20 dB gain
Noise: Output 100 uV unweighted 20 to 20 KHz
Damping Factor: 200
Slew: 100 V/uS
Input Impedance: 47 Kohm
Peak Current: 10 Amp output (200 Watts into 2 ohms) Independent of loudspeaker load phase.
Protection: Shutdown at 10 amps output
Idle Power draw: 200 Watts total.
Dimensions: 17” W x 17.4” D x 6” H
Weight: 46 pounds/21 kilograms
Price: $4,900 MSRP
More information about the XA25 at Pass Labs.