Headphones

While the OOR is short of the 'fiddle-ability' of some headphone amplifiers – I'm thinking here of the bright red SPL Phonitor xe [HFN Jul '21], with its crossfeed, angle and 'Laterality' controls (and also priced in the same ballpark) – it compensates for its simplicity with a sound of unusual openness and directness. Whichever headphones you plug into it, balanced or unbalanced, appear to have been given a shot of extra power – not just in level, although the OOR will drive them hard and extremely cleanly, but in terms of dynamic freedom and openness of expression.

Superior Strings
Playing Rosanne Philippens' sparkling recent recording of Haydn and Stravinsky with The Vondel Strings [Channel Classics CCS 43921; DXD], what's obvious from the off is the clarity on offer here, allied to a generous bass for the 'bigger fiddles', and the detailed, fresh sound of the soloist's violin both within and before the ensemble. The music is presented as a whole, with no odd instrumental tonality to upset the ear, and yet every element of the performance is open for inspection.

Yes, the OOR gives away a little warmth and lushness to Naim's Uniti Atom HE with recordings such as this, as I ascertained when running it (carefully!) in 'bypass mode' from the latter's balanced output, but the differences are such that the choice of headphones is more likely to be a deciding factor in the balance of the set-up. For example, used with the rich-sounding Bowers & Wilkins P9 Signature [HFN Mar '17], the OOR cut through some of the warmth to deliver marginally more detail, while with a set of rather drier Austrian Audio Hi-X55s the Atom Headphone Edition took the prize with its generosity of balance.

With Nao's poignant And Then Life Was Beautiful set [Little Tokyo Recordings/RCA/Sony Music 19439900512] the Ferrum amp is highly revealing of the singer's distinctive voice, while also delivering both substance and detail in the rich arrangements and production of the album. The result was a presentation with real presence, plus some superbly extended bass and crisp beats beneath Nao's often fragile-sounding and heartfelt vocals.

For The Fans...
This amp's ability to drive hard while giving great insight is firmly to the fore with Steely Dan's live Northeast Corridor [Universal UICY-16015], bringing out the ambience of what is, to be fair, a run through the greatest hits in front of a loyal fanbase. As one might expect, it's all pretty note-perfect, albeit with a bit of extemporisation here and there, but none the less enjoyable for all that. The ability of Ferrum's OOR amplifier to reveal all the threads of these performances, especially when driving the late-lamented Oppo PM-1 headphones in balanced mode, is never in doubt.

Rather less sparky – chilly in fact – is For Now I Am Winter, the 2013 electronica/classical crossover by Ólafur Arnalds [Mercury Classics 00289 481 0150], combining icy strings and driving beats. The OOR headphone amp really makes the most of the intertwining rhythms, the sheen of the string section, the deep bass and the sometimes stinging percussion to create a sound with bags of atmosphere and no shortage of interest.

This is especially obvious in the shifting moods of 'Brim' as it flows into the album's title track. Meanwhile the stripped-down 'Words Of Amber' finds the chilling solo piano beautifully set against a distant atmospheric background – if you want an unsettling sound lodged inside your head, then this is the place to find it.

Piano of a different kind is equally well handled with A Curious Feeling, the 1973 solo debut by Genesis key-tickler Tony Banks [Esoteric Recordings ECLEC 2160]. Here the sound is big and bold, refined and immaculately produced, and the OOR gets its teeth into all that prog detail and richness to fine effect – nowhere more than on the strikingly cinematic 'The Waters Of Lethe'.

Hi-Fi News Verdict
It's far from the only headphone amp in its price category, and many rivals offer more facilities, but if you want to play it simple, the OOR will please with its direct, communicative delivery via a wide variety of partnering 'phones. Avoid that bypass mode if you don't want nasty surprises and potential damage to partnering equipment – you've been warned! – and you won't go wrong here.