The Denon AH-D9200 is 24Ω at 105.0 dB/mW; the Denon AH-MM400 is 40Ω at 105.0 dB (no figure from the maker at all). This page is only about what they ask of an amplifier — not how they sound, which no specification on either sheet can tell you.
In amplifier terms these two are the same headphone. The gap between what they need for 100 dB is under half a decibel, which is smaller than the step between two clicks of most volume controls.
| Specification | AH-D9200 | AH-MM400 |
|---|---|---|
| Impedance | 24 Ω | 40 Ω |
| Sensitivity | 105.0 dB/mW | 105.0 dB |
| Sensitivity (voltage) | 121.2 dB/V | 119.0 dB/V |
| Power for 100 dB | 0.32 mW | 0.32 mW |
| Voltage for 100 dB | 87 mV | 0.11 V |
| Current for 100 dB | 3.6 mA | 2.8 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 3.00 Ω | 5.00 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
One caution before reading the rows. For Denon AH-MM400 the maker publishes no sensitivity figure at all. The number in the table was collected when this database was first built and has never been traced to a manufacturer document, so treat every row below it as an estimate rather than a specification.
Every source in the database that drives one of them drives the other. On power, the choice between these two changes nothing about what amplifier you need.
1 source is low enough in output impedance for the AH-MM400 under the one-eighth rule but not for the AH-D9200 (Shanling H5).
280 of the 280 sources here reach 100 dB on both. That count is about power only — the output-impedance and hiss lines above are separate questions, and a source can pass this one and fail those.
The gap between these two in decibels does not change with volume — it is a property of the two headphones. What changes is the size of the numbers, and it changes fast: every 10 dB costs ten times the power. The row that matters is the one nearest the level you listen at, and for most people that is nearer the top of this table than the bottom.
The AH-MM400 is more demanding than 37% of the 567 non-electrostatic models in this database; the AH-D9200 than 27%. Both figures use the same measure as the rest of the site: whichever runs out first against a 2 V, 100 mW dongle, voltage or power.
| dB SPL | AH-D9200 power | AH-D9200 voltage | AH-MM400 power | AH-MM400 voltage |
|---|---|---|---|---|
| 80 | 3.2 µW | 9 mV | 3.2 µW | 11 mV |
| 85 | 0.01 mW | 15 mV | 0.01 mW | 20 mV |
| 90 | 0.03 mW | 28 mV | 0.03 mW | 36 mV |
| 95 | 0.10 mW | 49 mV | 0.10 mW | 63 mV |
| 100 | 0.32 mW | 87 mV | 0.32 mW | 0.11 V |
| 105 | 1.0 mW | 0.15 V | 1.0 mW | 0.20 V |
105 dB is included because forum power figures are usually quoted there or higher. It is also a level that damages hearing in minutes — how many minutes is its own calculator.
| Source | Price | Headroom, AH-D9200 | Headroom, AH-MM400 | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 18.5 dB | 18.8 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 28.3 dB | 27.0 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR11 | $36 | 20.4 dB | 18.8 dB | 0.5 Ω | 8.0 µV |
Of the 280 sources here, 280 reach 100 dB on both. That is the easy axis. 69 of them also publish an output impedance low enough for both under the one-eighth rule and a noise figure that stays below the audible-hiss threshold with both — the rest either fail one of those or never printed the number at all, and 208 of them are in the second group.
The cheapest of the 69 is the JadeAudio JA11, at $20. It leaves 18.5 dB of headroom on the AH-D9200 and 18.8 dB on the AH-MM400, its output impedance is 0.5 Ω against a one-eighth limit of 3.00 Ω and 5.00 Ω, and its noise figure puts the hiss floor 14 dB and 16 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
Cheapest that satisfies three published numbers is not the same as best, and none of it is about how either headphone sounds. To put either model against a source this page does not mention, or to change the target loudness, use the amplifier matcher.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| AH-D9200 | 5-56.000Hz | not printed | not printed |
| AH-MM400 | nothing printed | — | — |
Denon prints 5-56.000Hz for the AH-D9200 and nothing at all for the AH-MM400.
So one side of this comparison has a frequency-response number and the other does not — which changes less than it looks. The range printed for the AH-D9200 comes with no tolerance beside it, and a range without a ±dB figure says nothing about how loud the headphone is at either end of it: thirty decibels down at the bottom and the sentence would still be true. On the only reading that would have made it a specification, the two sheets say the same amount: nothing.
None of this is a measurement. What each maker publishes, and what it is worth, is set out in the frequency response audit.
Each model has a page of its own with the full source list, the hiss estimate and the provenance of every figure above: Denon AH-D9200 and Denon AH-MM400. Each figure on this page is labelled on those pages with where it came from, including the ones Denon never published — what that maker publishes, counted.