We’re sort of saving the best until last because the Ausounds AU-Flex-ANC eschews the usual full-range dynamic driver, a collection of balanced armature drivers, or even a combination of the two. Instead, it features a small planar-magnetic drive unit for the midrange and high-frequencies, coupled to a dynamic driver for the bass. This is installed as a single module within the earphone itself. In theory, that should give the best of both worlds, combining the smooth mids and upper frequencies of a planar-magnetic with the energy, bass depth and oomph of dynamic drivers. There is no provision for tailoring the tonal balance of the two-in-one unit, so you need to like the overall sound the Ausounds earphones make; however, the sound has been designed to please the largest number of people.
In fact, the overall balance is pretty damn good. It’s perhaps a little too bassy for those used to the more light and lean sound that people often associate with audio – especially British audio, in particular British audio based around loudspeakers like the LS3/5a. On the other hand, many listeners find that classic British sound too lean and bass-light in and of itself. The balance here is not boomy or overly bass heavy; the AU-Flex-ANC has a fine sense of presence and authority in the lower registers and doesn’t lay that bass on too thick. Playing the obligatory ‘Chameleon’ by Trentmøller [The Last Resort, Poker Flat records] shows a deep, rumbling bassline without undue flab or filler. The bass has depth and drive (perhaps best described as ‘Phatness’) but it’s also controlled and even, and it gives a bassline an energy that is infectious, even when that bassline is coming from a cello in a string quartet.
More important from an audio enthusiast perspective, the midrange on up is excellent. The vocal clarity is extremely good, which is obviously incredibly important in what, ultimately, is both a musical performer and a communications device. Voices are clear and articulate with excellent diction, both in terms of listening to an operatic aria, a singer in a band, and vocal quality in telephone, Skype and FaceTime calls. This combination of strong bass and vocal articulation are often hard to reconcile; when you listen to ‘Because He Was a Bonny Lad’ by The Unthanks [Here’s The Tender Coming, Rabble Rouser records] the vocals are distinct and – because they are close-mic’d – the resonant tones of the singers are often easy to exaggerate, but not so here. These are fine folk voices, singing in pure harmony, but without that almost woolly overtone that can plague many loudspeakers and headphone systems.
This excellent midrange extends up to the treble too, which is extremely well balanced. The high-frequency extension is deft and never overblown, something that can be a problem with some IEMs. It’s not a ‘relaxed’ or a ‘laid-back’ sound, but instead presents an effortless and natural sounding treble. This is obviously good for classical, folk and jazz listeners – who want their acoustic instruments to be as natural sounding at all frequencies, it’s also important for those wanting sonic purity in their electric and electronic instruments. I want to hear the squealing drone tone of Public Enemy’s ‘Rebel Without A Pause’ [It Takes A Nation Of Millions To Hold Us Back, Def Jam] with as much accuracy as possible to give it that scorching aggression, just as I want to hear a piccolo or a violin with the same precision. Fortunately, that precision and accuracy is precisely what the AU-Flex-ANC gives you.
Most significantly, however, it’s the ability for the earphones to support and handle higher grade sound than normally expected through mobile wireless connections that makes these earphones soar. The sound benefits because there’s more cogency and presence to the sound compared to even the best of Bluetooth. This comes across best with more sparse recordings where the nearly wispy sound of the likes of Bebe’s Cambio del Piel [Warner] can sound watery and inconsistent on many compressed systems, but realistically this works with almost all kinds of music.