Both are desktop amplifiers, $150 against $160. 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 SMSL HO100 reaches 100 dB on 567 of the 567 models here, the PreSonus HP4 on 558.
| Specification | PreSonus HP4 | SMSL HO100 |
|---|---|---|
| Power into 32Ω | 69 mW | 1.5 W |
| Power into 150Ω | 52 mW | 354 mW |
| Power into 300Ω | 26 mW | 200 mW |
| Power into 600Ω | 13 mW | 100 mW |
| Output impedance | not published | <0.1 Ω |
| Output noise | not published | 1.3 µV |
| Price | $150 | $160 |
| Headphones it reaches 100 dB on out of 567 | 558 | 567 |
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 HP4 | SMSL HO100 |
|---|---|---|
| 32 Ω | Derived | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Derived | Published |
| 600 Ω | Derived | Published |
Only one of these two columns starts from a power rating. SMSL HO100 publishes one at 32 Ω, at 300 Ω and at 600 Ω; PreSonus HP4 publishes none at any of these four loads, so its column is worked out from power it published at other loads. Both are arithmetic on a maker’s own figures rather than guesses, and the method used for the PreSonus HP4 understates rather than flatters — but at 32 Ω, at 300 Ω and at 600 Ω are the only loads here at which its maker can be held to a figure.
What each of these labels means, and why a derived figure is still worth printing, is set out in how this data was built.
9 headphones reach 100 dB on the SMSL HO100 but not on the PreSonus HP4 — Moondrop COSMO, Moondrop PARA, Moondrop PARA 2, 6 more.
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 Shure SE846: SMSL HO100 has +46 dB of headroom there against +27 dB. 19 dB is about 87 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for PreSonus HP4 because that 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 HP4 headroom | SMSL HO100 headroom | PreSonus HP4 hiss | SMSL HO100 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +27 dB | +46 dB | not published | 17 dB |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +7 dB | +26 dB | not published | -3 dB |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +21 dB | +30 dB | not published | -5 dB |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +17 dB | +26 dB | not published | -10 dB |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +8 dB | +24 dB | not published | -11 dB |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +10 dB | +19 dB | not published | -16 dB |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +6 dB | +15 dB | not published | -21 dB |
| HiFiMAN Susvara | 60 Ω | 50 mW | +4 dB | +12 dB | not published | -23 dB |
The SMSL HO100 costs $10 more than the PreSonus HP4. Out of the 567 models here, that difference buys 9 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.
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 HP4 and SMSL HO100. Or put either against your own headphones in the source comparison tool.