Short answer
Both are desktop DAC/amps, $399 against $449.
The JDS Labs Element III MK2 reaches 100 dB on 567 of the 567 models here, the Cambridge Audio DacMagic 200M on 565.
| Specification | Cambridge Audio DacMagic 200M | JDS Labs Element III MK2 |
|---|---|---|
| Power into 32Ω | 300 mW | 2.3 W |
| Power into 150Ω | 65 mW | 584 mW |
| Power into 300Ω | 32 mW | 292 mW |
| Power into 600Ω | 16 mW | 146 mW |
| Output impedance | not published | 0.7 Ω |
| Output noise | not published | 2.51 µV |
| Price | $399 | $449 |
| Headphones it reaches 100 dB on out of 567 | 565 | 567 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Load | Cambridge Audio DacMagic 200M | JDS Labs Element III MK2 |
|---|---|---|
| 32 Ω | Published | Published |
| 150 Ω | Published | Published |
| 300 Ω | Derived | Derived |
| 600 Ω | Derived | Published |
Both makers publish a power rating. Cambridge Audio DacMagic 200M publishes at 32 Ω and at 150 Ω; JDS Labs Element III MK2 at 32 Ω, at 150 Ω and at 600 Ω. The other rows are worked out from those.
So the two columns are not equally firm row by row: at 600 Ω only the JDS Labs Element III MK2 figure is the maker’s own. On those rows the derived number is the one to doubt first.
2 headphones reach 100 dB on the JDS Labs Element III MK2 but not on the Cambridge Audio DacMagic 200M — Moondrop PARA, Symphonium Titan.
565 of the 567 models here reach 100 dB on both.
Headroom is at a 100 dB SPL peak.
The widest gap on the list is the Audio-Technica ATH-R70X: JDS Labs Element III MK2 has +21 dB of headroom there against +11 dB. 10 dB is about 9 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Cambridge Audio DacMagic 200M because that maker publishes no output noise figure.
| Headphone | Impedance | Needs | Cambridge Audio DacMagic 200M headroom | JDS Labs Element III MK2 headroom | Cambridge Audio DacMagic 200M hiss | JDS Labs Element III MK2 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +33 dB | +42 dB | not published | 22 dB |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +13 dB | +22 dB | not published | 2 dB |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +22 dB | +31 dB | not published | 1 dB |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +18 dB | +27 dB | not published | -4 dB |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +15 dB | +24 dB | not published | -5 dB |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +11 dB | +21 dB | not published | -11 dB |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +7 dB | +16 dB | not published | -15 dB |
| HiFiMAN Susvara | 60 Ω | 50 mW | +5 dB | +14 dB | not published | -17 dB |
The JDS Labs Element III MK2 costs $50 more than the Cambridge Audio DacMagic 200M. Out of the 567 models here, that difference buys 2 more models driven to 100 dB.
Nothing runs the other way: there is no axis here on which the cheaper of the two does better.
Only published figures count here; blank axes are counted separately.
Each in full: Cambridge Audio DacMagic 200M and JDS Labs Element III MK2.