Review: REV33 TrueSound

Firstly I would like to thank Nifty Audio for the loan unit, I always try to write honest reviews. There is no need for burn-in on this unit, it is purely a passive device, it is also a bit of a different product for me to review, but worth a read.

Gear Used:
Audio Opus #2 > Rev33 > Sennheiser HD-25 II

Packaging, Build Quality and Accessories:
The packaging is a nice simple brown card box, again this is a device for professionals so the box most likely won’t be kept. I like the very simple packaging however, and it looks good and does the job just fine.

Build quality is good, again this is a totally passive little device, it’s built for touring professionals so is built to last. The casing is plastic covered with rubber and the jack sockets feel solid. Not a lot I can say about the build quality.

Included accessories are the interconnect cable (3.5mm – 2.5mm) and as small leather pouch which holds the REV33 and has an elastic strap to attach it to your source of choice. Everything you need is included.

About the REV33:
Well I probably couldn’t tell you exactly how it works, and this is not my normal product to review, but I thought it was an interesting concept for touring musicians and sound engineers. So here is their website that explains how it works:

The general gist is that this reduces distortion and improves signal to noise ratio, which makes for a cleaner sound that is less fatiguing. This is mainly at high volumes that are used at concerts, and not one for audiophiles at home really.

So my testing took place mainly A/B’ing songs that I found to be fatiguing at high volumes out of my DAP.

The REV33’s effect is very subtle, it doesn’t try to alter the sound of your headphones (hence why you have to order the correct model for your headphones). 

Because of this you don’t lose any detail, and also due to it being passive there is no possibility of it adding any electrical noise. I think the effect of the REV33 is one that you wouldn’t notice straight away, it is one that you cannot hear easily, but what is offers is slightly better separation of instruments, and slightly better placement within the soundstage.

 Also the main thing it offers is less fatigue after listening at loud volumes for prolonged periods of time (I know you should not do this, but musicians quite often do due to noise levels and PA systems, which is who this is aimed at). I listened for quite some time at high volume levels and no fatigue.

The increased separation makes everything sound a little cleaner, less muddy. Taking the REV33 out of the chain you realise that is actually is making a small difference, everything sounds a little sharper and a little harsh in comparison.


(slight edit, the REV33 is for audiophiles and professionals alike, and as it is a passive device it works at all volumes equally, just the effect is more noticeable at louder volumes)

It has been really interesting testing the REV33, as I said it’s not my usual kind of product to review, and I was sceptical at first as I always think adding extra to the signal chain is bad, but when it comes to musicians and sound engineers, it is important to have good sound, but also important to look after your ears.

The REV33 does work, it doesn’t take anything away from the music, it also doesn’t add a flavour of its own, it lets the sound of your headphones shine through with slightly improved soundstage positioning and separation, but also without harshness or fatigue.

It's priced at £149.99 and for that, it might just save your hearing, at the very least you will suffer from less fatigue. And you cannot put a price on that.


  1. My next words might be overused but still, pretty cool review. This headphone is actually good for sound tripping. I would want to have one of these if only I have the money. :)


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