Short answer
Both are audio interfaces, $3500 against $2499.
The RME ADI-2 Pro EX reaches 100 dB on 567 of the 567 models here, the Audient Horizon 8P on 566.
| Specification | Audient Horizon 8P | RME ADI-2 Pro EX |
|---|---|---|
| Power into 32Ω | 986 mW | 1.9 W |
| Power into 150Ω | 278 mW | 540 mW |
| Power into 300Ω | 140 mW | 370 mW |
| Power into 600Ω | 71 mW | 185 mW |
| Output impedance | 10 Ω | 0.1 Ω |
| Output noise | not published | 2.18 µV |
| Price | $3500 | $2499 |
| 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 EX |
|---|---|---|
| Socket | no separate rating | 2 x 6.3 mm TRS (RME 'Advanced Balanced' mode uses both unbalanced jacks as one balanced pair) |
| Power into 32Ω | — | 4.2 W |
| Power into 300Ω | — | 1.4 W |
| 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 EX 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.
| Load | Audient Horizon 8P | RME ADI-2 Pro EX |
|---|---|---|
| 32 Ω | Derived | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Derived | Published |
| 600 Ω | Published | Derived |
Both makers publish a power rating. Audient Horizon 8P publishes at 600 Ω; RME ADI-2 Pro EX at 32 Ω and at 300 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 Audient Horizon 8P figure is the maker’s own and at 32 Ω and at 300 Ω only the RME ADI-2 Pro EX figure is the maker’s own. On those rows the derived number is the one to doubt first.
1 headphone reaches 100 dB on the RME ADI-2 Pro EX but not on the Audient Horizon 8P — Symphonium Titan.
510 headphones are left alone by the RME ADI-2 Pro EX 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 Campfire Audio Andromeda 2020: RME ADI-2 Pro EX has +25 dB of headroom there against +19 dB. 6 dB is about 3.8 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 EX headroom | Audient Horizon 8P hiss | RME ADI-2 Pro EX hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +39 dB damping | +45 dB | not published | 21 dB |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +19 dB damping | +25 dB | not published | 1 dB |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +29 dB damping | +31 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 | +24 dB | not published | -6 dB |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +18 dB | +22 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 | +13 dB | not published | -18 dB |
The Audient Horizon 8P costs $1001 more than the RME ADI-2 Pro EX, 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 EX 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 EX 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 EX.