Short answer
Both are desktop amplifiers, $1600 against $1700.
The Wells Audio Milo reaches 100 dB on 567 of the 567 models here, the SPL Phonitor se on 566.
| Specification | SPL Phonitor se | Wells Audio Milo |
|---|---|---|
| Power into 32Ω | 1.0 W | 12.0 W |
| Power into 150Ω | 3.1 W | 3.1 W |
| Power into 300Ω | 4.2 W | 1.5 W |
| Power into 600Ω | 2.1 W | 767 mW |
| Output impedance | 0.18 Ω | 0.1 Ω |
| Output noise | 5.48 µV | 1.5 µV unverified |
| Price | $1600 | $1700 |
| Headphones it reaches 100 dB on out of 567 | 566 | 567 |
| Load | SPL Phonitor se | Wells Audio Milo |
|---|---|---|
| 32 Ω | Published | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Derived | Derived |
| 600 Ω | Derived | Derived |
Both makers publish a power rating. SPL Phonitor se publishes at 32 Ω; Wells Audio Milo at 32 Ω. The other rows are worked out from those.
The two publish at the same loads, which is the one case where the rows of this table can be read straight across.
1 headphone reaches 100 dB on the Wells Audio Milo but not on the SPL Phonitor se — Symphonium Titan.
566 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 HiFiMAN HE400se: Wells Audio Milo has +31 dB of headroom there against +20 dB. 11 dB is about 12 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Wells Audio Milo because that maker publishes no output noise figure.
| Headphone | Impedance | Needs | SPL Phonitor se headroom | Wells Audio Milo headroom | SPL Phonitor se hiss | Wells Audio Milo hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +38 dB | +49 dB | 29 dB | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +18 dB | +29 dB | 9 dB | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +33 dB | +39 dB | 7 dB | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +39 dB | +35 dB | 3 dB | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +20 dB | +31 dB | 2 dB | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +32 dB | +28 dB | -4 dB | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +28 dB | +24 dB | -8 dB | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | +15 dB | +22 dB | -10 dB | not published |
The Wells Audio Milo costs $100 more than the SPL Phonitor se. Out of the 567 models here, that difference buys 1 more model 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: SPL Phonitor se and Wells Audio Milo.