Benchmark AHB2 Power Amplifier - Silver - 19 Inch Rackmount

The AHB2, Built for a Rack

This is the AHB2 in Benchmark's 19-inch rackmount chassis. Same amplifier and the same measurements, built into a faceplate that bolts straight into a standard equipment rack at 2U of height.

It makes 100 watts per channel into 8 ohms, 190 into 4 and 259 into 2, both channels driven, and 380 watts into 8 ohms bridged to mono. Benchmark builds it around THX's Achromatic Audio Amplifier technology.

The rack version measures 19 inches wide and 10.62 deep, and weighs 13.5 pounds. The standard AHB2 is 11 inches wide and 12.5 pounds. So this is the one to order if the amplifier is going into a rack rather than onto a shelf.

Inside the Chassis

The distortion figure is the headline: THD+N below 0.00013% at full rated output. Signal-to-noise reaches 132dB A-weighted in stereo and 135dB in mono, and dynamic range is 130dB unweighted across the audible band.

Those are not marketing numbers. They are the reason listeners report hearing detail in familiar recordings they had never noticed before. The amplifier is simply not adding anything on top of what the record already holds.

Frequency response runs from 0.1Hz to 200kHz. Damping factor is 350 at 20Hz into 8 ohms. Two balanced XLR inputs are fitted at 50k ohms, with three gain settings — 9.2dB, 17.0dB and 23dB — so the amplifier can be matched to a professional source or a domestic preamplifier.

What Reviewers Are Saying

Stereophile lists the AHB2 in its Recommended Components, 2026 edition, marked both as a value recommendation and as a long-term reference. It is "Named for the late Allen H. Burdick, the engineer whose work formed the basis for its design".

Kalman Rubinson found the practical result in his listening: "much more apparent low-level detail in already-familiar recordings", which Stereophile credits to "the Benchmark's evident noiselessness".

Who Is This Amplifier Best For?

• Your system lives in a rack — the 19-inch faceplate at 2U bolts straight in, where the standard AHB2's 11-inch chassis would need a shelf or a tray.
• You want to hear the recording, not the amplifier — THD+N below 0.00013% and a 132dB noise figure mean the amplifier adds essentially nothing between your preamplifier and your speakers.
• Your speakers drop to low impedance — 259 watts per channel into 2 ohms, both channels driven, from a chassis that weighs 13.5 pounds and needs no fan.
• The rack has a heat problem — a feed-forward design wastes very little as heat, so this amplifier does not need the clearance or the airflow a conventional Class AB design of this ability would.
• You want separates — volume and input switching live in the preamp or streamer/DAC ahead of it; choose from our preamplifiers

How Does It Connect to Your System?

Bolt it into the rack at 2U, allowing 10.62 inches of depth plus cables. Connect your preamplifier to the balanced XLR inputs and set the gain switch to match it.

Register the amplifier with Benchmark when it arrives — that takes the US warranty from one year to five, at no cost.

Pairs Well With

Here are some great companions:

• Preamplifier: Required, and the natural next decision — see our Preamplifiers.
• Speaker Cables: Carry the current properly — see our Speaker Cables.
• Interconnects: Balanced XLR is what this amplifier wants — see our Interconnect Cables.
• Audio Rack: Give the amplifier a proper shelf — see our Audio Racks.

Frequently Asked Questions

How is this different from the standard AHB2?

Only the chassis. This version has a 19-inch rackmount faceplate at 2U and measures 10.62 inches deep, weighing 13.5 pounds. The amplifier inside is identical.

How much power does it make?

100 watts per channel into 8 ohms, 190 into 4 and 259 into 2, both channels driven. Bridged to mono it makes 380 watts into 8 ohms and 518 into 4.

How much rack space does it need?

Two rack units, 19 inches wide and 10.62 inches deep. Allow extra depth behind for cable runs.

Does it need forced-air cooling?

The feed-forward design wastes very little energy as heat, so it does not need a fan or the clearance a conventional Class AB amplifier would.

What are the three gain settings for?

9.2dB, 17.0dB and 23dB, so the amplifier matches a professional source or a domestic preamplifier without the volume control sitting at an extreme.

What warranty does it carry?

One year as standard, which Benchmark extends to five years in the US simply by registering the amplifier.

See It in Action

Benchmark Media Systems explains running the AHB2 bridged or in stereo:

Z Reviews puts the AHB2 through a full review:

Why Audio Advisor?

• 40+ Years of Expertise — Since 1981, we've helped over a million music lovers find the right gear.
• 60-Day Money-Back Guarantee — Take your time. Listen, enjoy, and make sure it's right for you.
• Real Experts, Real Help — Our team is here to answer your questions at 800-942-0220, weekdays 9am–6pm EST.
• Free Shipping — On orders over $49, delivered to your door.
• Flexible Payment Options — Financing available so you can start listening now.

Learn More

Want to learn more about power amplifiers, balanced connections, or building a separates system? Visit our Learning Center for guides, tips, and expert advice.