Short answer
Both are audio interfaces, $3500 against $2199.
The RME ADI-2 Pro FS R reaches 100 dB on 567 of the 567 models here, the Audient Horizon 8P on 566.
| Specification | Audient Horizon 8P | RME ADI-2 Pro FS R |
|---|---|---|
| Power into 32Ω | 986 mW | 3.0 W |
| Power into 150Ω | 278 mW | 634 mW |
| Power into 300Ω | 140 mW | 317 mW |
| Power into 600Ω | 71 mW | 158 mW |
| Output impedance | 10 Ω | 0.1 Ω |
| Output noise | not published | 2.18 µV |
| Price | $3500 | $2199 |
| Headphones it reaches 100 dB on out of 567 | 566 | 567 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Balanced | Audient Horizon 8P | RME ADI-2 Pro FS R |
|---|---|---|
| Socket | no separate rating | balanced |
| Power into 32Ω | — | 11.8 W derived |
| Power into 300Ω | — | 1.3 W derived |
| Output impedance | — | 0.2 Ω |
| Output noise | — | not published |
| Headphones it reaches 100 dB on out of 567 | — | 567 |
Only the RME ADI-2 Pro FS R has a separate balanced rating from its maker; through it, it reaches 100 dB on 567 of the 567 models here. The Audient Horizon 8P may still have a balanced socket — its spec sheet simply gives no figure for one, so there is nothing to put beside it. Derived figures are worked out from the loads the maker did publish.
| Load | Audient Horizon 8P | RME ADI-2 Pro FS R |
|---|---|---|
| 32 Ω | Derived | Upper bound |
| 150 Ω | Derived | Upper bound |
| 300 Ω | Derived | Upper bound |
| 600 Ω | Published | Upper bound |
These two columns are not the same kind of number, and that matters more than the gap between them. Audient Horizon 8P publishes a power rating (at 600 Ω); RME ADI-2 Pro FS R publishes no power figure at any load, only a maximum output voltage, so every milliwatt in its column is a ceiling worked out from that voltage.
A ceiling assumes the amplifier holds that voltage into the load, and nothing on RME ADI-2 Pro FS R’s own sheet says it does. It is the most flattering reading available, and it is used here only because the alternative is a blank. Where the RME ADI-2 Pro FS R column looks the stronger of the two, treat the difference as unproven rather than measured. 24 of the 280 sources here are in that position, with no published power rating at any load.
1 headphone reaches 100 dB on the RME ADI-2 Pro FS R but not on the Audient Horizon 8P — Symphonium Titan.
510 headphones are left alone by the RME ADI-2 Pro FS R under the one-eighth rule but coloured by the Audient Horizon 8P (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 507 more).
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: RME ADI-2 Pro FS R has +25 dB of headroom there against +20 dB. 4 dB is about 2.7 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Audient Horizon 8P because that maker publishes no output noise figure.
| Headphone | Impedance | Needs | Audient Horizon 8P headroom | RME ADI-2 Pro FS R headroom | Audient Horizon 8P hiss | RME ADI-2 Pro FS R hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +39 dB damping | +43 dB | not published | 21 dB |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +19 dB damping | +23 dB | not published | 1 dB |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +29 dB damping | +32 dB | not published | -1 dB |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +24 dB | +28 dB | not published | -5 dB |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +20 dB damping | +25 dB | not published | -6 dB |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +18 dB | +21 dB | not published | -12 dB |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +13 dB | +17 dB | not published | -16 dB |
| HiFiMAN Susvara | 60 Ω | 50 mW | +11 dB damping | +15 dB | not published | -18 dB |
The Audient Horizon 8P costs $1301 more than the RME ADI-2 Pro FS R, and on these three axes the money buys nothing: among the 567 models here there is not one that the Audient Horizon 8P handles and the RME ADI-2 Pro FS R does not — not on power, not on the one-eighth rule, not on hiss. The traffic runs the other way: the cheaper RME ADI-2 Pro FS R drives one model to 100 dB and leaves 510 alone under the one-eighth rule that the Audient Horizon 8P does not.
Only published figures count here; blank axes are counted separately.
Each in full: Audient Horizon 8P and RME ADI-2 Pro FS R.