Skip to product information
1 of 4

Ferrum OOR Headphone Amplifier

Ferrum OOR Headphone Amplifier

SALE Sold out
Regular price $1,995 In stock now!
Regular price $1,995 Sale price $1,995 In stock now!
Shipping calculated at checkout.

Product questions? Found a lower price?

Let us know: 909.931.9686 or chat.

Trade-in Form

Tell us about yourself

Tell us about your trade-in item

Please note: We are unable to accept cables, tables, and carts.

View full details
  • "It's hard to find an amp that's this neutral and still so pleasant, engaging, and musical."

    Susvara and Abyss owners, rejoice! One of Grover's personal favorite solid-state headphone amps, the Ferrum OOR with Hypsos linear hybrid power supply, puts out a huge 8 W into 60 ohm balanced (6 W single-ended.) The fully adjustable Hypsos power supply takes the OOR to the next level, and the PSU can be used on its own for a number of amps, DACs, streamers, and other products.

Ferrum OOR Balanced Headphone Amplifier

By the designers of Mytek, a balanced head amp with an amazing 8 W of power to drive even the most demanding headphones. Made in Poland.

Easily drive even your most low impedance, high-current headphones such as Susvara, Abyss, LCD-5, and so on with this 8 W fully balanced headphone amp by Polish brand HEM, founded by the designers behind Mytek. 

Use the XLR inputs for a true balanced signal from end to end, or turn a single-ended signal into a truly balanced one via the RCA inputs. The simple front panel design offers just three knobs to control the most important settings.

The Ferrum sound is all about a balanced and very transparent sound signature, while ensuring there is no listening fatigue. The power amplifier section is fully discrete and was developed in-house to dial in the exact sound that was sought. 

HYPSOS Power Supply
While the OOR performs beautifully right out of the box, we strongly recommend buying it in a bundle with the matching HYPSOS external power supply. This is a hybrid switching and linear supply designed to offer the advantages of both techniques, low ripple and noise as well as fast transient response and high efficiency.

Connected by the Ferrum Power Link cable, the HYPSOS will unleash unheard-of musicality from the combination with OOR.


  • Fully balanced analog headphone amplifier
  • Proprietary discrete power amp technology
  • External PSU available and highly recommended 
  • Balanced 4-pin XLR and unbalanced RCA headphone outputs


Gain(Balanced; SE): -4 dB, + 6dB, +16 dB;  -10 dB, 0 dB, 10 dB

Inputs: XLR, RCA, 2.5 mm DC connector centre positive, proprietary 4-pin DC connector

Outputs: Balanced 4-pin XLR, 6.35 mm jack

Output Power (300 Ω, 60 Ω)
Single Ended: 400 mW, 2 W
Balanced: 1.600 mW, 8 W 

Input Impedance: 94 kΩ

Preamp Output Impedance (XLR, RCA): 44 Ω, 22 Ω 

Headphone Output Impedance: < 0.3 Ω

Dimensions (WDH): 8.6" x 8.1" x 2" (21.7 x 20.6 x 5 cm)

Weight:  3.97 lb (1.8 kg)