Ferrum Audio OOR Review

Sound – Headphones

For this section, all of the headphones were connected to the Ferrum Audio OOR in a balanced way, except for the DT1990 Pro.

Hifiman HE6SE

A really great combo. The OOR has more than enough power for these cans and they really make the HE6SE shine. Great detail, great speed, excellent layer and a natural amount of body is what you get here. The OOR and HE6SE combo is technically strong and musical at the same time. What I like most here is the bass delivery and layering, as well as the vocals and treble presentation. This combo has great synergy and it’s fully recommended.

Meze Audio Empyrean

The Empyrean is a very full sounding headphone that carries a full body from top to bottom. It has bigger bass and a good amount of warmth and smoothness in the delivery. If you like the Empyrean, it’s probably because of this specific tuning.

I for one love the Empyrean but I can’t deny that it sometimes is a bit too much in regards to body/bass and it can be overwhelming at times. What the OOR does here is tame the Empyrean in this regard. You get a lighter sounding Empyrean in regards to bass and body and the neutral tuning of the OOR takes away a bit of the Empyrean’s warmth. I have to say I like both versions of the Empyrean’s sound but for those who like its tuning but find it a bit heavy and warm, this amplifier could be the perfect solution.

Rosson RAD-0

Another headphone I have really enjoyed listening to with the OOR is the Rosson RAD-0. I really like the tuning of the RAD-0 but like so many, I just wish it was a bit lighter and more comfortable.

The synergy with the OOR is really nice and you get a tight, and fast sound, with a natural amount of body and excellent speed. The bass and vocals here are really impressive as well as the layering in the bass and mids. IT’s a very musical combo and the OOR is in perfect control at all times. This for me might be one of the best amplifiers for the RAD-0 which I have had the pleasure to listen to.

Sennheiser HD800(S) & HD660S

Many of my friends and colleagues are surprised when I tell them I like the sennheiser HD800 and HD660S, but with the right amplifier they absolutely shine. And with the right amplifier I tend to mean warmer and full sounding solid state amplifiers and OTL tube amplifiers.

If you’ve read the review up to here you will know by now that the OOR isn’t like that at all. And as a result I have mixed feelings with these headphones. The combos are not bad, but I have heard the Sennheiser headphones sound better. I especially have this feeling with the HD800S and the HD660S. The combo with the original HD800 is actually quite nice, especially in high gain where the bass and vocals are impressive. But all-in-all I don’t like the Senn & OOR combo as much as the other combos in this review.

Kennerton Wodan

The Kennerton Wodan is a high end headphone which is easy to like and which is very easy to listen to. The synergy with the OOR is quite nice, though the Wodan doesn’t sound most linear here with elevated bass and forward vocals.

It’s a technically strong and musical combo but I do feel the fatigue coming up after a few hours of listening to the combo. This is mainly caused by the bass and vocals, but that’s not really the OOR’s fault. So all-in-all it’s not the very best match, unless this sounds like your preferred type of tuning.

Beyerdynamic DT1990 Pro

I wasn’t really sure what to expect with this combo, but it turns out the synergy is quite nice.

The Beyerdynamic DT1990 PRO delivers great detail, excellent speed and impressive quality bass with to level layering. It’s no surprise the mids are a bit lighter here but they are spacious, dynamic and natural. The vocals are bit more to the front by I love the energy they carry. The treble section is energetic and lively. This was actually my biggest worry for this combo, but as I have said the OOR’s treble section is rather easygoing. As a result it matches well with the DT1990 Pro and it’s a combo which I like a lot. It’s not always easy to get a good synergy with the DT1990PRO, but this combo does it for me.

Sound – Without Hypsos

Without the Hypsos and with a normal PSU, the Ferrum Audio OOR still sounds very good but everything is toned down a little.

You have to think in the direction of the extension, precision, extension and note decay. Without the Hypsos you still get a high quality sound, but it’s a little less spacious and more intimate, closed in.

It’s not like a black and white difference, but the difference is clearly there. It’s easy to hear as well and everyone I spoke to agrees about it. It’s one of the very first times that a special dedicated PSU has made me hear such a clear difference and improvement.

Therefor it’s very easy for me to recommend the Hypsos as PSU for the OOR, and use the FPL connection. Yes it’s about €1K on top of the amp’s price, but at this price level that’s not such a huge step either. Spoil yourself and get the very best sound out of the OOR, you won’t regret it.

End Words

Ever since the Ferrum Audio OOR arrived at the HFN headquarters I have been using it nonstop, together with the Hypsos power supply. The OOR is an addictive amplifier with a high technical level and all the power you’ll ever need. Ferrum has managed to make the OOR sound precise yet musical and that’s exactly what they were going for.

The Ferrum Audio OOR has an excellent price/performance ratio even though it sets you back €2K, or even €3K with the supplementary Hypsos PSU. It’s not cheap but for a high end unit, it’s actually fairly affordable and it easily plays along with even more expensive amplifiers. If you have this kind of budget available and you like this type of neutral and technically strong tuning, I wouldn’t hesitate to order the Hypsos PSU with it.

All-in-all a very good amplifier and I look forward to seeing what Ferrum Audio comes up with next. A matching DAC maybe? To the Recommended Buy List it goes! The OOR also wins our 2021 Amplifier of the year award!

Page 1: HEM, OOR, Design, Build quality & Amp layout, Specs

Page 2: Sound – Intro, General, Single Ended vs Balanced, Classics

Page 3: Sound – Headphones, Without Hypsos, End Words