First Listen: Aurender Flow portable headphone amp/DAC/preamp

Most audiophiles associate the name Aurender with the firm’s range of highly accomplished music servers, and rightly so. More than many competitors in the field, Aurender has demonstrated that it is keenly attuned to the needs and wants of serious music lovers—listeners who pay careful attention to even the smallest and finest aspects of sound quality and of product design. But now, thanks to the advent of a lovely new product named the Aurender Flow ($1,295 in the US), Aurender may soon become known the maker of an exceptional—and exceptionally elegant—portable headphone amplifier/DAC/preamp. If Aurender’s Flow has its way with things, then performance-minded headphonistas may soon start to consider the Flow as a possible alternative (and a somewhat lower-priced alternative) to the superb Chord Electronics Hugo. Here’s why I offer that comment.

The Flow is similar in size to the Hugo, though differently shaped (the Hugo is configured to be used in ‘landscape’ orientation, with its widest side toward the listener, while the Flow is meant to be used in ‘portrait’ orientation). Among the more obvious visual differences between the Flow and the Hugo involve the fact that the Flow is noticeably thicker than the Hugo, has a bead-blasted matte silver finish (much like certain Constellation audio components do, has a gently undulating wave-contoured top surface, and sport a large-diameter, ring-shaped volume control at the centre of which is an enourmously informative status display window.

Let me come right out and say it; the Flow is drop dead gorgeous to look at and a tactile delight in day-to-day use. If you are the sort of listener who likes products that combine refined aesthetics and fine sound quality in one package, the Flow might be ideal for you. But more importantly, it is versatile, easy to use, technically sophisticated, and sounds very good.

In practice, the flow gives users options that many other headphone amp/DAC makers do not. Thus it offers three basic source inputs:

• Optical S/PDIF,
• USB 2.0/3.0, or
• Its own (optional) onboard mSATA storage.

That last item is an unusual one, but the Flow’s designers had the foresight to reserve interior space (and appropriate socketry) within the Flow’s chassis to allow users to add mSATA storage if they so desire. Thus, in a sense, the Flow could be viewed not just as an amp/DAC, but as a player, too.

Most DAC makers claim their products are Window/Mac compatible, but the Flow goes further to support USB audio playback from iOS and Android devices, too! Accordingly, the Flow’s Host menu offers five options:

• USB2 (for connecting to PCs with USB 2.0 ports),
• USB3 (for connecting to PCs with USB 3.0 ports),
• Mac,
• iOS, and
• anDR (which of course stands for Android).

In support of all these options, the Flow ships with a rather impressive collection of accessories including:

• A high-quality screwdriver (used for opening the Flow’s chassis to install mSATA drives, if desired),
• A high-capacity USB power charger (to charge the Flow’s beefy 4450 mAH Samsung Li-ion battery),
• A 6.35mm headphone plug to 3.5mm headphone jack adapter,
• A 6.35mm headphone plug to stereo RCA jacks adapter cable (for those instance where owners might wish to use the Flow as a standalone DAC or DAC/preamp),
• A standard TOSLINK to mini-optical adapter cable,
• A mini-USB to mini-USB cable (ideal for use with most Android devices),
• A short USB A to USB 3.0 adapter cable, and
• A longer USB A to USB 3.0 adapter cable.

About the only thing not included (for obvious reasons) is the Apple USB Camera Kit that is required to establish Apple Lightning to USB connections.

In keeping with Aurender practice, the Flow offers a number of subtle but sonically worthwhile features and user-selectable options—options that some makers of portable amp/DACs tend to overlook. For example, the Flow gives users the choice of USB power charging modes:

• CHG+ (which always charges up the Flow whenever a charging capable USB host is connected),
• CHG- (which forces the Flow not to be charged when a USB host is connected, but does allow charging from a USB power charger), and
• CHGA- (which is an “Automatic” smart-charging mode that allows charging from a USB host, but only when music is not playing.

The DAC section of the Flow uses the popular and well-regarded ESS9018K2M DAC chip, which supports PCM playback at resolutions up to 32-bit/384kHz, or DSD playback (via DoP mode) for DSD64 and DSD 128 files. Filter settings for digital playback are surprisingly extensive, including:

For PCM playback,

• pcm0 (a fast roll-off PCM filter),
• pcm1 (a minimum phase PCM filter said to “virtually eliminate ringing from signals”), and
• pcm2 (a slow roll-off PCM filter that is “an in-band filter” where “output signal will be slightly attenuated).

For DSD playback,

• dsd0 (a noise-shaping filter with bandwidth or BW = 47.4kHz),
• dsd1 (BW = 50kHz),
• dsd2 (BW = 60kHz), and
• dsd3 (BW = 70kHz).

Finally, the Flow gives users three analogue output options:

• VAR (where variable analogue output is enabled via the headphone jack),
• 2V (a fixed-level, 2V analogue line-out setting), or
• 5V (a fixed-level, 5V analogue line-out setting).

My point is supplying all this detail is to give you some idea of just how meticulous and thorough Aurender’s engineers have been in configuring the Flow for use by difficult-to-please, detail-minded Audiophiles. In short, the Flow should please even the more finicky enthusiasts amongst us.

Another aspect of the Flow that deserves mention is usability. Honestly, some products as complex as the Flow have been known to arrive at the Hi-Fi+ office with not all of their features documented or working as described. For the journalist, this often means a certain amount of “forensic product investigation” is in order, simply to figure out how the unit does (or doesn’t) work.  But the Aurender is not like this at all; in fact, our sample has proven to be one of the best-documented and most easily used audio products of its type that we’ve ever encountered.

Right out of the box, absolutely everything about the Flow worked as advertised and with no set-up glitches at all. When you’ve encountered as many “almost working” audio products as we have over the years, then you’ll quickly realise the Flow’s flawless, trouble-free operation is actually a pretty big deal.

How does it sound? Well, I’ll save detail comments for the full-length Hi-Fi+ review that will follow in a few weeks’ time, but I’ll give you my general first impressions for now.  First off, I would say that in comparison to some devices I’ve heard that use the ESS 9018K2M DAC, the Flow manages to achieve a more natural and organic sound (as apposed to a detailed but perhaps slightly ‘clinical’ sound) than most. Since this is also a characteristic I associated with the wonderful Chord Hugo, I consider it a worthy accomplishment on Aurender’s part.

Second, I would say that the Flow really let’s you hear and savour the differences in resolution and musical nuance that today’s better high-res digital audio files afford. In a sense, then, the Flow’s sound quality seems to scale upward dramatically as you provide source materials that have increasing levels of musical ‘data density’. This characteristic, as you can imagine, make the Flow exciting to listen through because, at its best, it seems geared toward helping listeners tap all that higher-res recordings have to offer.

As to power, I’m not ready to comment on the Flow’s output capabilities just yet, other than to say that it seemed to have (just) enough oomph for the fairly power-hunger HiFiMAN HE-560 headphones, yet was quiet enough for use with the wildly sensitive JH Audio Roxanne custom-fit in-ear monitors. So far, so good. Stay tuned for more details in our upcoming Hi-Fi+ review.

Until then, Happy Listening to one and all.