{"product_id":"ferrum-oor-headphone-amplifier","title":"Ferrum OOR Headphone amplifier","description":"\u003cp\u003eThe \u003cstrong\u003eFerrum OOR\u003c\/strong\u003e is a reference-class headphone amplifier engineered with the same obsessive attention to detail that earned Ferrum its EISA award pedigree. Built around a unique discrete output stage, a fully balanced signal path, and a proprietary internal power supply derived from the acclaimed HYPSOS, OOR raises the bar for what intimate, analogue listening through your favourite headphones can sound like.\u003c\/p\u003e\n\u003ch2\u003eA Unique Output Stage\u003c\/h2\u003e\n\u003cp\u003eOOR's output stage is unlike anything found in a typical headphone amplifier. Rather than a conventional Class A or Class AB design, Ferrum's engineers developed a proprietary topology that sits between the two. Independent monitoring circuits prevent either output transistor from ever fully switching off, keeping both away from the most non-linear region of their characteristics. The result is dramatically lower distortion than a standard Class AB design, without the heat and inefficiency of full Class A operation.\u003c\/p\u003e\n\u003cp\u003eThis output stage is further linearised by a discrete current feedback amplifier with approximately 60 kHz of open-loop bandwidth (-3 dB) and almost 1 MHz of closed-loop bandwidth (-3 dB). This wide open-loop bandwidth — achieved through a two-pole compensation scheme — keeps distortion unusually flat across the entire audio spectrum, a characteristic simply not achievable with IC-based headphone amplifiers.\u003c\/p\u003e\n\u003ch2\u003eFully Balanced Throughout\u003c\/h2\u003e\n\u003cp\u003eThe entire signal path in OOR is fully balanced from input to output, with no transformers or inductors in the signal path. The input stage — an internal preamplifier handling gain and volume — converts single-ended signals to balanced internally, so even RCA sources benefit from fully balanced amplification. The signal is only converted back to single-ended at the unbalanced outputs themselves, preserving maximum signal integrity throughout.\u003c\/p\u003e\n\u003ch2\u003eInternal Power Supply\u003c\/h2\u003e\n\u003cp\u003eOOR's internal power supply is the technological heir of HYPSOS. Low-noise switching regulators with double-stage input and output filtering feed fast transient response linear LDOs — with separate LDOs for each channel for improved channel separation. Eight independent power rails in total ensure that analogue and digital sections never interfere with one another.\u003c\/p\u003e\n\u003cp\u003eOOR also features two DC power inputs: a standard 5.5\/2.5 mm DC jack and a proprietary 4-pin connector compatible with Ferrum's HYPSOS. When connected via the dedicated FPL (Ferrum Power Link) cable, HYPSOS measures voltage directly on OOR's motherboard rather than at the cable output — allowing it to stabilise voltage even further along the power path for a meaningful uplift in performance.\u003c\/p\u003e\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eUnique discrete output stage\u003c\/strong\u003e\u003cbr\u003eA proprietary topology between Class A and Class AB, with independent transistor current monitoring for dramatically reduced distortion across the audio spectrum.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDiscrete current feedback amplifier\u003c\/strong\u003e\u003cbr\u003e~60 kHz open-loop bandwidth and ~1 MHz closed-loop bandwidth via two-pole compensation — delivering unusually flat distortion performance not found in IC amplifiers.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFully balanced signal path\u003c\/strong\u003e\u003cbr\u003eNo transformers or inductors in the signal path. Single-ended inputs are converted to balanced internally, with conversion back to single-ended only at the RCA outputs.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHYPSOS-derived internal power supply\u003c\/strong\u003e\u003cbr\u003eEight independent power rails with separate LDOs per channel, low-noise switching regulators, and double-stage filtering for a supremely quiet noise floor.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMade for HYPSOS\u003c\/strong\u003e\u003cbr\u003eConnect via the proprietary FPL cable and HYPSOS performs 4T voltage sensing directly on OOR's motherboard, squeezing every last drop of performance from both components.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIndustrial design\u003c\/strong\u003e\u003cbr\u003eDesigned by a specialist industrial design studio in Warsaw, with custom-designed volume knobs and gain switches refined through extensive prototyping for optimum ergonomics and visual cohesion. The signature lacquered corten steel logo ties OOR into the wider Ferrum ecosystem.\u003c\/p\u003e\n\u003ch2\u003eWhy Choose OOR?\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eProprietary discrete output stage — unlike any IC-based headphone amplifier on the market\u003c\/li\u003e\n\u003cli\u003e~60 kHz open-loop bandwidth for flat distortion across the full audio spectrum\u003c\/li\u003e\n\u003cli\u003eFully balanced signal path from input to output, with no transformers or inductors\u003c\/li\u003e\n\u003cli\u003e8 W balanced output power into 60 Ω — drives virtually any headphone with ease\u003c\/li\u003e\n\u003cli\u003eEight independent internal power rails with separate LDOs per channel\u003c\/li\u003e\n\u003cli\u003eTwo DC power inputs — compatible with included supply or HYPSOS for elevated performance\u003c\/li\u003e\n\u003cli\u003eSix-layer PCB with two dedicated ground planes and common mode chokes for EMI attenuation\u003c\/li\u003e\n\u003cli\u003eEISA award-winning pedigree — engineered by the team behind HYPSOS and WANDLA\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eAbout Ferrum\u003c\/h2\u003e\n\u003cp\u003eDesigned and engineered by \u003cstrong\u003eFerrum \/ HEM\u003c\/strong\u003e in Warsaw, Poland. Ferrum was founded in early 2020 with a clear mandate: combine sustainability, durability, and quality into compact, attractive packages — focused entirely on delivering the best possible audio experience at an affordable price. Built on over 20 years of digital audio expertise and a history of collaboration with Mytek Digital on world-class DAC technology, Ferrum brings unmatched engineering pedigree to every product. OOR raised the bar for intimate, analogue headphone listening — and it remains one of the finest headphone amplifiers available at any price.\u003c\/p\u003e\n\u003ch5\u003eSpecifications\u003c\/h5\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eOperation\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eFully balanced, proprietary discrete power amp technology\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eGain\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eBalanced: -4 dB, +6 dB, +16 dB\u003cbr\u003eSingle ended: -10 dB, 0 dB, +10 dB\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eInputs\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eXLR, RCA, 2.5 mm DC connector centre positive, proprietary 4-pin DC connector\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eOutputs\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eBalanced 4-pin XLR, 6.35 mm jack\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eFrequency response\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e20 Hz – 100 kHz (+\/- 0.1 dB)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eOutput power (single ended)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e400 mW into 300 Ω; 2 W into 60 Ω\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eOutput power (balanced)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e1,600 mW into 300 Ω; 8 W into 60 Ω\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eInput impedance\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e94 kΩ\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eOutput impedance (single ended)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e22 Ω on pre-amp\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eOutput impedance (balanced)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e44 Ω on pre-amp\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eOutput impedance (headphones)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e\u0026lt; 0.3 Ω\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003ePower consumption\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eIdle \u0026lt; 15 W\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003ePower adapter\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e100–240 VAC to 22–30 VDC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eDimensions\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e21.7 cm × 20.6 cm × 5 cm \/ 8.6″ × 8.1″ × 2.0″ (W × D × H)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e","brand":"Ferrum Audio","offers":[{"title":"Default Title","offer_id":48560509255897,"sku":"Ferrum OOR Headphone amplifier","price":250000.0,"currency_code":"BDT","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1337\/7789\/files\/FerrumOOR_frontDAC.webp?v=1776897000","url":"https:\/\/gearsforears.com\/products\/ferrum-oor-headphone-amplifier","provider":"Gears For Ears","version":"1.0","type":"link"}