The industry’s most expensive wattage claim now has a very awkward benchmark.
A watt of Class A bias costs $131 in a Pass Labs XA30.8 and $236 in a $99,000 Gryphon Apex. In a pair of Dan D’Agostino Momentum Z monoblocks, the same watt runs $1,563, and the pair costs $125,000.
That twelvefold spread exists because the high-end amplifier industry treats Class A watts as a luxury commodity, with no agreed-upon threshold for when more of them stop improving the sound.
Bill McKiegan, president of Dan D’Agostino Master Audio Systems, just named one.
But the ceiling he’s proposing sits far below what competitors across that twelvefold spread deliver.
A Quiet Admission at $125,000
The Momentum Z delivers 500 watts into 8 ohms. Only about 40 of those watts, “I believe,” operate in Class A, McKiegan said during an interview at Audio Show Deluxe 2026.
That figure matters, but it needs context. For instance, D’Agostino’s official Momentum Z specifications do not publish a Class A wattage figure. And, they list idle power consumption at 35 watts, which is well below what a fixed 40-watt Class A bias would normally require.
This means McKiegan’s comment may describe peak, sliding, approximate, or manufacturer-specific Class A behavior rather than a constant 40-watt operating region.
Put to a calculator, his claim still points in the same direction. A speaker rated at 90 dB sensitivity climbs past 100 dB at one meter with 40 watts behind it, a volume McKiegan called “frighteningly loud.”
He estimated that 99% of listening with a 90 dB speaker happens within the Momentum Z’s Class A range.
To be clear, McKiegan did not claim the amplifier degrades above 40 watts of Class A. Instead, he questioned whether anyone listening at 108 dB, a volume well past the threshold of discomfort, would notice the difference between Class A and Class AB operation.
After three decades of selling Class A amplification, he just told the industry that the spec it charges a premium for may stop being audible well before the competition runs out of watts.
Forty Watts Under a Microscope
Forty watts into a 90 dB sensitive speaker yields roughly 106 dB at one meter, which is louder than standing next to a running lawnmower.
Pull back to a typical listening seat at three meters and room reflections still leave the level around 99 to 103 dB, deep into “frighteningly loud” territory.
Most people never get close to those levels, though. Audiophile listening surveys consistently place average volumes between 75 and 85 dB SPL, which requires less than one watt from the amplifier.
Benchmark Media’s own measurements, for one, put average music playback power at approximately one watt, with brief peaks reaching 25 to 65 watts for milliseconds at a time.
That line lands harder against what most amplifiers actually deliver in Class A. According to engineer Rod Elliott, the typical power amp operates in Class A only up to about 5 to 10 milliwatts before transitioning to Class B.
In practice, the Momentum Z’s claimed 40-watt Class A region is not incrementally above that baseline.
It is thousands of times above it, well past the point where crossover distortion enters the picture.
Sensitivity, impedance, and distance still matter.
A harder-to-drive speaker with 86 dB sensitivity instead of 90 would eat four decibels of headroom, but that adjustment changes the margin rather than the underlying scale.
More Watts, More Zeros
If 40 watts of Class A operation covers the levels where music is actually heard, the pricing spread across the industry becomes harder to justify.
| Amplifier | Class A Bias | Price | Cost per Class A Watt* |
|---|---|---|---|
| Pass Labs XA30.8 | 30W/ch | $7,875 (stereo) | $131 |
| Gryphon Apex Stereo | 210W/ch (pure) | $99,000 (stereo) | $236 |
| D'Agostino Momentum Z | ~40W/ch | $125,000 (mono pair) | $1,563 |
For this table, “Class A watt” means the output range where an amplifier remains in Class A before transitioning to Class AB, unless the product is pure Class A across its rated output. So the comparison is not pretending the amplifiers are identical.
In fact, Pass Labs reports a Class A operating range, Gryphon markets the Apex as pure Class A, and D’Agostino’s figure comes from McKiegan’s interview claim rather than a published bias specification.
Gryphon’s Apex sits at the far end of the scale, delivering 210 watts per channel of pure Class A at a weight of 202 kilograms, roughly 450 pounds, because dissipating that much continuous heat requires transformer iron and heatsink mass that most manufacturers avoid.
What do those extra watts produce? Two hundred and ten watts into a 90 dB speaker yields approximately 113 dB at one meter, well into the range where sustained exposure causes permanent hearing damage.
Meanwhile, D’Agostino lands in the middle on claimed Class A range but at the top on price, reflecting the Momentum Z’s total power reserves, build quality, current delivery, and brand positioning rather than its Class A specification alone.
Where the Class A Defense Stops Short
Not everyone in the industry agrees that the question is settled. Nelson Pass, whose amplifier designs are built around the principle that higher bias produces better sound, argues that amplifiers should be biased at ten times the typical signal level to achieve their best performance.
If average listening power is one watt, his rule suggests ten watts of Class A bias should suffice. By that metric, D’Agostino’s claimed 40-watt range provides four times the recommended headroom.
Plus, his own entry-level Class A design, the XA30.8, delivers 30 watts, already triple what the 10x rule recommends.
Pass does build more powerful Class A models, but the floor of the line already sits close to McKiegan’s stated threshold.
On the other hand, Gryphon makes no such concession, acknowledging that pure Class A demands “heavy transformers, very large heatsinks, large quantities of expensive parts and costly assembly,” then building the product anyway and treating the physical cost as proof of engineering commitment rather than diminishing returns.
Still, the strongest empirical case for Class A comes from Benchmark Media’s ABX testing, where a listener achieved a perfect 25 out of 25 score identifying crossover distortion at just 10 milliwatts.
That result validates Class A operation at the power levels where people actually listen.
Krell Was Already There
Krell, the company that helped turn high-power Class A into an audiophile status symbol, was already engineering around the same practical limit.
A later owner calculation circulated on DIYAudio placed the KSA-250’s continuous Class A output at approximately 28.6 watts, or roughly 11% of its rated power.
The figure is not an official Krell specification, and the methodology may vary, so it should be treated as historical context rather than confirmation.
Aside from that, Krell’s own engineering makes the stronger point. Sustained Plateau Biasing, developed in the 1990s, adjusted the amplifier’s bias in four discrete steps based on signal demand instead of holding full-power Class A constantly.
When signal demand rose, the system ramped bias upward and held it for 20 to 30 seconds before stepping back down.
Even inside the company that built the Class A legend, constant full-power Class A was treated as a problem to manage rather than a requirement to preserve.
The paradox is not that D’Agostino changed course. The more telling point is that the amplifier culture he helped create was already making room for the same conclusion McKiegan is now stating more plainly.
Four Decades, One Number
Four data points from four different decades all land in the same neighborhood. A 1990s Krell flagship biased at 28.6 watts and a Pass Labs designer whose published 10x rule puts the threshold at 10.
A measurement lab that puts the sonic threshold at milliwatts and a $125,000 amplifier’s president who says 40 watts covers 99% of listening.
These sources had no reason to converge. Pass founded First Watt on the premise that if the opening watt is wrong, more power won’t fix it, and even his mainstream XA series starts at 30 watts of Class A.
McKiegan’s company charges $1,563 per Class A watt and could justify a higher figure. Benchmark’s data could have shown the advantage scaling with power. Instead, each landed at or below 40 watts through separate engineering, separate measurements, and separate decades.
No one has published the blind comparison that could prove a higher threshold matters. Not Gryphon, which sells 210 watts of pure Class A. Not D’Agostino, and not any independent lab.
After decades and hundreds of thousands of dollars in pricing premiums, that absence is conspicuous.
He builds a 500-watt amplifier for the first 40 watts. The question is whether his competitors’ extra hundreds are anything more than heat.