Sound Quality

Gordon Kelly

By Gordon Kelly



Our Score:


While audio manufacturers may extol the technical virtues of their products, the real differentiator in high end IEMs is their sound signature. That said, we still expect the tech specs to be up to scratch and the Aero's are with a frequency range of 20Hz – 18KHz, impedance of 19.7 ohm and sensitivity of 116 dB SPL (at 1mW). When it comes to that sound signature, though, it will provoke a love/hate reaction depending on your choice of music.

Much like Etymotic and GenevaSound, Unique Melody opts for a signature focused on accuracy. This makes the Aero's superb for classical music, jazz, indie and 'unplugged' music. It is possible to hear the detail within track arrangements, isolating particular instruments or honing in on the vocals. Settle down with some Duke Ellington, Philip Glass or Belle & Sebastian and you'll be in heaven.


Where the Aeros run into problems though is when you switch to music with a greater focus on bass. Pick any big beat artist, heavy metal (or even rock) band or some dance and the sensation is the Aeros are holding back. Certainly it is possible to tweak the sound through an equaliser, but this isn't desirable on a regular basis and many modern MP3 players/phones don't offer this functionality in any case.

This development is something of a surprise since the Aeros pack triple balanced armature drivers with a passive three-way crosser (Single High/Mid, Dual Low) - on paper more than enough to power through whatever material you throw at them. Part of the problem is amplification. More drivers require more power and the Aeros seem particularly power hungry. Plug them into a laptop or a decent amp and the problem is reduced, but it doesn't go away completely.


The schizophrenic nature of the Aeros is perfectly born out in a track such as The Dresden Doll's 'The Mouse and the Model'. The delicate piano of the intro and soft vocals are delightfully detailed, but when the military-esque drums kick in around the minute mark you're suddenly left cold and this is further accentuated as the six minute track folds in the guitars and bass, and the vocals switch to their staccato conclusion.

Don't get us wrong, Unique Melody has not created a poor sound signature and we appreciate that some people do prefer a more trebly output. What's more the quality of the Aeros is not to be doubted - the detail and soundstage can be phenomenal. It's just that they are specialists which excel at particular music types. Given these monitors are custom moulded they only need to suit your music tastes and no-one else so if that fits your bill then go for it. Then again if you're music collection is diverse you'll be in trouble.

Which brings us to another significant talking point: the nature of hard shell custom moulds themselves...

Mark Booth

June 24, 2011, 4:30 pm

I have to say I completely agree for a music listening experience. The MP3 generation is used to having soft foam or silicon tips, so the thought of going to hard plastic with less noise isolation would feel like a step back to me, let alone the comfort issue.

I have always had comfort/fit issues with off the shelf UE/Shures, so decided on the ACS T1 and all I can say is wow! Fit is incredible and they warm to body temperature in seconds, leaving you with a very natural feel. And the bonus is you can listen at any volume (bleedingly loud if that floats your boat), even in a library, and no one has the faintest idea. Complete sound isolation :)


June 24, 2011, 8:04 pm

100% agree. Silicon moulds have huge advantage over hard shells. Once you've tried silicon it is virtually impossible to go back to hard shells.


June 27, 2011, 8:14 am

Hmm, I'm a little unsure about this article. For one, there's no comparison against the Shure SE535's, which aren't custom moulded but are in the same target price range (and also triple driver), and there's also grammatical errors and broken links in it as well. C'mon guys, you can do better than this...


June 28, 2011, 7:59 am

Dear Yan, that's a poor tone. Had you read the links to the ACS T2 review ( you would have seen the T2 is directly compared to the SE535 and wins by a country mile. It is no longer the gold standard and therefore not the principle point for comparison, especially for a custom mould.

While no longer responsible for subbing I see no errors over 1,500 words and having written over 5,000 articles for TrustedReviews in more than 6 years I feel when commenting you can do better than this.


June 28, 2011, 8:01 am

As irony would have it, please ignore the closing bracket - picked up as part of the hyper link.


July 1, 2011, 7:38 am

Sorry for the tone, but that's just what I felt when reading this - poor.

Yes, I have read the ACS T2 review, though I had to hunt for it myself as the link in the article was broken at the time. It's been fixed now, but still, we shouldn't have to read every article published by TR so we can keep a track of A is better than B which is better than C which is better than D, just to compare A and D.

Besides, this misses the point - even if the 535's are not the gold standard in IEMs, they (alonside the GR10s) are still the best non-custom IEMs TR has reviewed. It seems negligent not to compare in any way a new pair of custom IEMs with what remains the best non-custom IEMs in the same target price range. Certainly many readers (including myself) would love to know how they compare, especially given the RRP on the 535's have dropped over £100 now.

Finally, there's still grammatical errors in the article, slight as they might be (you're, your) but added to the broken link and lack of detail, I just felt the article didn't tell me anything I wanted to know. Given the target audience of people most likely to consider buying a £500 pair of custom IEMs are also the same group most likely to consider (or already own) top of the line non-custom IEMs, some tips on how or why to choose one over the other would have been appreciated by many.

The only sentence that even mentions the benefits of customs say the UM's have a claimed noise isolation of 25dB, but then not mentioned is the fact that the 535's have a claimed noise isolation of 37dB (!) so where's the benefit? It all just seems confused and one-sided at best.


July 1, 2011, 7:45 am

The other thing that wasn't mentioned was even if the 535's no longer compare in terms of sound quality, how do they compare in terms of value? The 535's can be had for £290 now in a bricks-and-mortar store, nearly £200 less than the Aeros - and you can get silicon sleeves for them. Should they still even be considered?

August 27, 2013, 8:15 pm

With a hard shell there is no give so the seal is easily broken. It also means they are more tiring to wear over long periods.

comments powered by Disqus