Ferrum OOR
Ferrum OOR
A powerhouse in a compact chassis — the Ferrum OOR. Specifically designed to meet the demands of the Susvara, it can effortlessly drive virtually any headphone on the market, delivering an exceptionally dynamic and detailed sound.
Ferrum OOR
Fully balanced headphone amplifier with preamp functionality — built for control, dynamics and transparency
Designed specifically with demanding headphones like the HIFIMAN Susvara in mind, Ferrum OOR delivers 8 watts into 60 ohms in balanced operation — in a chassis that still fits comfortably on a desk.
Sonically, OOR is remarkably flexible: not only thanks to three gain levels, but also because it can be used in bypass mode, where the volume control (and its sonic footprint) is routed around via a separate signal path. Pair it with the optional HYPSOS power supply and you can also adjust the supply voltage between 22–30 V, shifting the character from “smooth yet detailed” to “ruthlessly present” — assuming your headphones can reveal it.
An endgame contender, and genuinely versatile thanks to its preamp capabilities.
OOR will drive virtually any headphones effortlessly to the max of their potential, while preserving the essence of the music it amplifies. Ultra low distortion, zero fatigue, huge dynamics and unrivaled detail translate into long-term enjoyment. OOR makes something that’s genuinely difficult to achieve feel completely natural.
Truly Balanced
The signal path stays truly balanced using the XLR inputs — and becomes truly balanced using the RCA inputs.
Ease of use
Only three knobs on the front panel to control the most important settings.
Ferrum Power Link
OOR performs extremely well right out of the box. But it’s made to excel above and beyond when used together with HYPSOS. Using the Ferrum Power Link (FPL) connection, HYPSOS can operate at its maximum, unlocking an even more effortless sense of musicality from the pairing.
Superior control
Perfected steering of output transistors protects them and never lets them turn off, reducing distortion to inaudible levels and keeping them ready to unleash power instantly — crucial for big dynamics, control and authority.
Enhanced transparency
The whole design is focused on a balanced and very transparent sound signature, making listening fatigue something of the past.
Discrete design
The discrete power amp technology is developed in-house to achieve the best possible analog quality.
Technical Specifications
| Gain (dB) | balanced -4 dB, +6 dB, +16 dB / single ended -10 dB, 0 dB, 10 dB |
| Operation | Fully balanced, proprietary discrete power amp technology |
| Inputs | XLR, RCA, 2.5 mm DC connector centre positive, proprietary 4-pin DC connector |
| Outputs | Balanced 4-pin XLR, 6.35 mm jack |
| Frequency Response | 20 Hz – 100 kHz 0.1 dB |
| Output Power (Single Ended) | 400 mW into 300 Ω, 2 W into 60 Ω |
| Output Power (Balanced) | 1.600 mW into 300 Ω, 8 W into 60 Ω |
| THD on balanced output | 0.00011% / -119 dB, 1 mW into 50 Ω; 0.00028% / -111 dB, 100 mW into 50 Ω |
| THD on unbalanced output | 0.00008% / -122 dB, 1 mW into 50 Ω; 0.00028% / -111 dB, 100 mW into 50 Ω |
| Dynamic range | 130 dB (A-weighted) |
| Input Impedance | 94 kΩ |
| Output Impedance (Single Ended, preamp) | 22 Ω on pre-amp |
| Output Impedance (Balanced, preamp) | 44 Ω on pre-amp |
| Headphone Output Impedance | < 0.3 Ω |
| Power Consumption | Idle < 15 W |
| Power Adapter | 100/240 V AC to 22-30 V DC |
| Dimensions (W×D×H) | 8.6 x 8.1 x 2.0 inch / 21.7 x 20.6 x 5 cm |
| Weight | 1.8 kg / 3.97 lbs |
