The AKG K240 MKII is 55Ω at 91.4 dB/mW; the AKG K52 is 32Ω at 95.1 dB/mW. This page covers what they ask of an amplifier, not how they sound.
The K240 MKII needs 3.7 dB more than the K52 to reach the same loudness — 7.2 mW against 3.1 mW.
| Specification | K240 MKII | K52 |
|---|---|---|
| Impedance | 55 Ω | 32 Ω |
| Sensitivity | 91.4 dB/mW | 95.1 dB/mW |
| Sensitivity (voltage) | 104.0 dB/V | 110.0 dB/V |
| Power for 100 dB | 7.2 mW | 3.1 mW |
| Voltage for 100 dB | 0.63 V | 0.31 V |
| Current for 100 dB | 11.5 mA | 9.8 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 6.88 Ω | 4.00 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
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 K240 MKII under the one-eighth rule but not for the K52 (Shanling H5).
280 of the 280 sources here reach 100 dB on both.
The K240 MKII is more demanding than 92% of the 567 non-electrostatic models in this database; the K52 than 76%.
| dB SPL | K240 MKII power | K240 MKII voltage | K52 power | K52 voltage |
|---|---|---|---|---|
| 80 | 0.07 mW | 63 mV | 0.03 mW | 31 mV |
| 85 | 0.23 mW | 0.11 V | 0.10 mW | 56 mV |
| 90 | 0.72 mW | 0.20 V | 0.31 mW | 99 mV |
| 95 | 2.3 mW | 0.35 V | 0.98 mW | 0.18 V |
| 100 | 7.2 mW | 0.63 V | 3.1 mW | 0.31 V |
| 105 | 23 mW | 1.12 V | 9.8 mW | 0.56 V |
| Source | Price | Headroom, K240 MKII | Headroom, K52 | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 3.8 dB | 9.9 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 12.1 dB | 18.1 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR11 | $36 | 3.8 dB | 9.9 dB | 0.5 Ω | 8.0 µV |
Of the 280 sources here, 280 reach 100 dB on both. 70 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 cheapest of the 70 is the JadeAudio JA11, at $20. It leaves 3.8 dB of headroom on the K240 MKII and 9.9 dB on the K52, its output impedance is 0.5 Ω against a one-eighth limit of 6.88 Ω and 4.00 Ω, and its noise figure puts the hiss floor 31 dB and 25 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| K240 MKII | 15 - 25000 | not printed | not printed |
| K52 | 18 - 20000 | not printed | not printed |
AKG prints 15 - 25000 for the K240 MKII and 18 - 20000 for the K52.
Neither range has a tolerance printed beside it, so a wider range on one sheet is not deeper bass or more treble.
Not a measurement; maker by maker.
Both have a page of their own. In full: AKG K240 MKII and AKG K52. Every figure on this page comes from what AKG published, or is derived from it — what that maker publishes, counted.