Both are audio interfaces, $199 against $299. This page puts them side by side on the only three things a maker can be held to — power, output impedance and noise — and then asks the question that actually matters: which headphones do they treat differently?
The PreSonus Quantum ES 2 reaches 100 dB on 561 of the 567 models here, the PreSonus Studio 68c on 558.
| Specification | PreSonus Quantum ES 2 | PreSonus Studio 68c |
|---|---|---|
| Power into 32Ω | 106 mW | 86 mW |
| Power into 150Ω | 22 mW | 56 mW |
| Power into 300Ω | 11 mW | 28 mW |
| Power into 600Ω | 5.6 mW | 14 mW |
| Output impedance | not published | not published |
| Output noise | not published | not published |
| Price | $199 | $299 |
| Headphones it reaches 100 dB on out of 567 | 561 | 558 |
A figure marked not published is missing from the maker’s own material, which is not the same as being good or bad. Where one of these two publishes a number and the other does not, the comparison on that axis cannot be made at all — and saying so is more useful than guessing.
| Load | PreSonus Quantum ES 2 | PreSonus Studio 68c |
|---|---|---|
| 32 Ω | Upper bound | Derived |
| 150 Ω | Upper bound | Derived |
| 300 Ω | Upper bound | Derived |
| 600 Ω | Upper bound | Derived |
Neither column is a power rating, and the two are not even weak in the same way. The PreSonus Quantum ES 2 figures are ceilings worked out from a maximum output voltage, on the assumption that the amplifier holds it into the load. The PreSonus Studio 68c figures are worked out from figures its maker did publish — power at other loads, or the voltage printed beside it. The second method understates; the first flatters. That is the wrong way round for reading the table straight across, so a gap in favour of the PreSonus Quantum ES 2 is the one to doubt.
What each of these labels means, and why a derived figure is still worth printing, is set out in how this data was built.
3 headphones reach 100 dB on the PreSonus Quantum ES 2 but not on the PreSonus Studio 68c — Moondrop PARA 2, Moondrop VENUS, Symphonium Triton.
558 of the 567 models here reach 100 dB on both. That is a power count and nothing more; whether either source suits a given headphone also depends on the two lines above.
The counts above say how many models the two treat differently. This says by how much. The same 8 headphones appear on every page of this kind, ordered from the easiest to drive to the hardest, so a row can be read across pages as well as across columns. Headroom is at a 100 dB SPL peak.
The widest gap on the list is the Audio-Technica ATH-R70X: PreSonus Studio 68c has +11 dB of headroom there against +7 dB. 4 dB is about 2.5 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for PreSonus Quantum ES 2 and PreSonus Studio 68c because neither maker publishes no output noise figure. That is a gap in the specification, not a quiet amplifier, and it is left blank here rather than filled with a plausible number.
| Headphone | Impedance | Needs | PreSonus Quantum ES 2 headroom | PreSonus Studio 68c headroom | PreSonus Quantum ES 2 hiss | PreSonus Studio 68c hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +29 dB | +28 dB | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +9 dB | +8 dB | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +18 dB | +22 dB | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +13 dB | +17 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +10 dB | +9 dB | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +7 dB | +11 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +2 dB | +6 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | +1 dB | +4 dB | not published | not published |
The PreSonus Studio 68c costs $100 more than the PreSonus Quantum ES 2, and on these three axes the money buys nothing: among the 567 models here there is not one that the PreSonus Studio 68c handles and the PreSonus Quantum ES 2 does not — not on power, not on the one-eighth rule, not on hiss. The traffic runs the other way: the cheaper PreSonus Quantum ES 2 drives 3 models to 100 dB that the PreSonus Studio 68c does not.
Everything in this paragraph counts only figures the two makers published. An advantage on an axis one of them leaves blank cannot be counted, and is not counted — how often that happens is its own page.
Each has a page of its own with every power figure traced to what the maker published and a full headphone list: PreSonus Quantum ES 2 and PreSonus Studio 68c. Or put either against your own headphones in the source comparison tool.