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Dream ticket to ride: Xiaomi’s Mi A1 smartphone

  • Wired or wireless? For portable audio idealists, the audio signal losslessly carried in the analogue domain between portable player and headphone – custom IEM, universal IEM or (low impedance) over-/on-ear is the only way. But it doesn’t end there…

    If the manufacturer hasn’t already beaten us to the punch, the idealist porta-fi-er sidesteps the smartphone’s 3.5mm headphone socket by strapping on a Lightning- or microUSB/A-connected DAC/amp. Think: Chord Mojo or iFi micro iDSD Black Label. One look at the resulting bulk raises quite reasonable questions about pocketability and what happens when the phone rings. Even for an idealist, a two-fer held to one’s ear is plain ridiculous.

    Enter the digital audio player (DAP), the majority of which offer file-based playback from microSD cards inserted into their undercarriage. Some are controlled by a touchscreen. Others are not.

    Market leader Astell&Kern offers integrated Tidal streaming via a bespoke-coded solution that, at the record labels’ request and frustratingly for a go-anywhere music player, doesn’t permit off-line content. For smartphone-like Tidal app behaviour we look to DAPs from Onkyo and Pioneer that run Android OS. The Google Play Store app gives us Spotify, Soundcloud, Mixcloud, Tidal, Qobuz, Deezer et al.

    Two years ago, I put my own cash down on Sony NW-ZX2, not because it was the best-sounding DAP available for the money and not only because it bested the sound of an iPhone’s audio circuitry. I dropped the best part of US$1300 in Tokyo’s Yodobashi Camerabecause the NW-ZX2’s Android OS didn’t force me to surrender the streaming services I’d been enjoying back on the iPhone.

    This points us at the DAP category’s fundamental weakness: a DAP is a second device to carry and keep charged. As the now defunct Pono player reminds us, a second device is fine for idealists, but not for mainstreaming pragmatists.

    Walking the middle ground are dongle-DACs like AudioQuest’s DragonFly Red/Black. Connected to a smartphone’s USB or Lightning port these thumb-drive sized DACs side step the phone’s own D/A conversion and headphone amplification for superior sound quality without the extra bulk.

    However, experience tells us that not all Android devices spill ones and zeros from their USB port (it’s a bit of a lottery) and for iOS devices, the requisite Lightning-to-USB adapter is both expensive (US$29) and fragile – I’ve gone through two in a year.

    The need for a sometimes bulky second device significantly weakens the porta-fi idealist’s case for going wired. That these same second devices often come at significant expense give pragmatists like yours truly significant pause: as a passenger on a noisy U-Bahn or a Friedrichstrasse pedestrian, am I really hearing all that a high-end DAP can deliver, especially when switching over from a custom fit IEM (that offers good passive noise isolation) to a universal IEM (that doesn’t).

    And if I’m going to draw on full-size headphones for listening to those Berghain playlists during my Berlin walkabouts, it’d be wise to consider wireless options from the likes of Sony, Bowers & Wilkins, V-Moda, Sennheiser and Bose where bespoke-fit amplification, D/A conversion and streaming functionality are housed inside each earpiece.

    With all the electronics housed in the headphone, only a smartphone is required with options to control playback – local and streaming – or accept/end incoming phone calls from the press of an earcup button. On convenience and real world integration, wireless headphones are the pragmatists choice.

    Furthermore, as with active loudspeakers, in stripping the end user of amplifier and DAC choices, sound quality can be DSP-optimised in ways not possible with direct-wired portable rigs. The most common of which is noise cancellation where microphones monitor external noise to allow the headphones to generate an inverted waveform that cancels out the original disturbance. This is most effective when those external noises are continuous and lower of frequency: the drone of an airplane; the background noise on a train. Less so with the up and down of nearby cafe conversations.

    For this porta-fi pragmatist, the audible benefits brought by the Sony MDR-1000X’s noise cancellation far outweigh the double loss(y) encoding of offline Spotify (Ogg Vorbis) and an iPhone 6S Plus highest quality Bluetooth codec (AAC).

    Even with a FLAC file loaded onto a microSD card and slotted into the Sony NW-ZX2, Bluetooth doesn’t (yet) have the bandwidth to stream it without first psycho-acoustically compressing the FLAC file’s contents with a lossy codec. And this is where Bluetooth headphones become a confusing mess for many consumers. The lossy codec used in any given Bluetooth audio connection is the best available and common to both devices: player/smartphone and headphone.

    As previously covered on these pages, Bowers & Wilkins’ marketing team make a big noise about the PX’s aptX (HD) support but say nothing of aptX (HD)’s irrelevance to iPhone users whose Apple hardware only offers up SBC and AAC. Thankfully, B&W had the foresight to specify AAC support in the PX.

    It’s not much better in the Android world where only a handful of models support aptX and those currently supporting aptX HD can be counted on one hand (whilst holding a pencil).

    B&W’s PX and an iPhone will auto-negotiate any Bluetooth audio pairing to use AAC to give us better sound quality than the catch-all SBC. But AAC comes up a soupcon short on aptX’s audible finesse, as heard from an aptX-fuelled connection between PX and Macbook. Yes, you read that right: Apple put aptX support in their MacOS devices (Macbooks, iMacs etc) but not iOS devices (iPhones and iPads).

    The Bowers and Wilkins PX’s companion smartphone app tells us that this headphone’s target market isn’t so much deskhounds as road warriors: pedestrians, public transport trippers and frequent flyers. In other words, smartphone users.

    Sony have gone a similar route with the MDR-1000X successor, the WH-1000XM2, whose smartphone app, like B&W’s, applies different noise cancelling profiles according to travel mode. The Sony app’s Sense Engine pulls this stunt automagically; or it can be applied manually as one must with the PX.

    In an earlier piece, I noted how the more stylish B&W had the sonic edge on the Sony. The PX offer  a greater sense of transparency and kick harder on dynamic contrasts. The Sony win out on everything else: comfort, noise cancellation, earpad control reliability and – not to be underestimated – carry case robustness. For me, this makes the Sony the better choice for long haul flights but the B&W the pick-up-n-go when moving around town.

    Why not stick to the iPhone as a Sony/B&W wireless headphone source and call it a day? After all, we get a very decent sounding AAC Bluetooth stream from both setups.

    Answer: even a porta-fi pragmatist suffers the occasional bout of FOMO – fear of missing out. This gives rise to a new category of listener: between the porta-fi idealist and the porta-fi pragmatist sits the optimising porta-fi pragmatist: s/he doesn’t pursue cost- or bulk-no-object solutions but seeks to maximise the Bluetooth headphone experience as dictated by the available hardware.

    In 2018, the road to Bluetooth headphone nirvana is full of twists and turns. Codec support is all over the map. Every source device and headphone comes with some degree of compromise. My aim of late has been to minimise those compromises as they relate to the two best premium Bluetooth headphone models: the Sony WH-1000XM2 (and MDR-1000X) and the B&W PX.

    I was in need of a portable device that maximised not only the B&W PX and Sony MDR-1000X / WH-1000XM2’s sound quality but also offered a better listening experience as it might relate to a Music-First Audiophile.

    With a Bluetooth connection sitting between source (smartphone or DAP) and sink (headphone), the need for hi-res audio support matters less than ever. My porta-fi priorities are FLAC playback from a microSD card plus access to one or more streaming services. Once again, pragmatism trumps idealism.

    If that sounds too nebulous, let’s put a fork in the first casualty, the Apple iPhone. Why? Two unbridgeable compromises: 1) no aptX (HD) or LDAC support and 2) no microSD card slot. Getting FLAC files onto an iPhone is a fiddly business. Once you’ve spent several years working with the modern day magic of microSD cards, it’s hard to return to the in-app iTunes drag-n-drop or FTP transfer demanded by the likes of FLAC Player.

    Stepping up as the next contender came the Sony NW-ZX2. A DAP that predictably ticks the micro-SD card slot box but also offers Google Play Store access (hello Spotify, Tidal etc.) *and* LDAC Bluetooth support, the latter seeing the Sony MDR-1000X convey more audible finesse and refinement than the AAC-restricted iPhone.

    This DAP’s first dealbreaker, albeit minor, stems from a lack of WH-1000XM2 agreeability caused by Sony’s indifference to supporting the NW-ZX2 long term with on-going OS updates. This DAP still runs a 2013 version of Android: Jelly Bean 4.2.2, incompatible with the Sony Headphone app called on by the MDR-1000X’s successor.

    As for the B&W, aptX is MIA. But so too is AAC. When paired with the Sony DAP, the PX fall back on SBC to sound more tonally washed out than they do when AAC paired with an iPhone.

    My next move was to eye an Astell&Kern portable. Two more affordable models – the AK70 MKII (US$699) and AK300 (US$599) – both offer an aptX HD Bluetooth output but their custom operating systems don’t permit installation of B&W or Sony’s control app.

    The real deal-breaker is that any Sony or Astell&Kern or whatever-manufacturer DAP is a second device to carry. The AK70 registers its physical presence at 132g. The NW-ZX2 weighs in at 235g. The AK300 tips the scales at a porky half kilo. Pass.

    Time then to turn our attention to the world of Android smartphones. Here again the Bluetooth source devil has burrowed deep in the device details. One of Android’s weak points is its lack of uniformity. Smartphone manufacturers not only look to hardware for market differentiation but also software, often foisting their own UI customisations on (oft-) unsuspecting users. Samsung’s Android implementation isn’t the same as Sony’s or HTC’s.

    This leads to what we might more kindly term ‘different Android flavours’. Your preference is your own but mine is for no flavour at all: pure, unadulterated stock Android, as previously delivered by Google’s own Nexus and Pixel models.

    The Pixel 2 meets the Bluetooth codec brief with aptX HD support enabled out of the box and Sony’s LDAC arriving via the Oreo 8.0 update. Sony has ‘gifted’ LDAC to the Google OS to promote its own Bluetooth headphone hardware. A fair trade. We can expect to see Android smartphone manufacturers roll out Android Oreo updates throughout the course of 2018. The Pixel 2’s compromises are two fold: mainstreamers will likely lament the absence of a 3.5mm headphone socket. For this commentator’s portable audio-focussed brief, the lack of a microSD card slot said, “Close…but no cigar”.

    Looking back to Q3 2017, screenshots of Oreo developer builds had already made their way onto various Android-focussed news sites. Being heavily implied was that aptX and aptX HD codec support would also be part of the forthcoming cookie-munching deal. It’s easy to mistake such rumour mongering as news. I know I did. But in going deeper into Google for more information on Orea’s Bluetooth codec set I turned up a jewel: the (Xiaomi) Mi A1 smartphone.

    The Mi A1 is this Chinese electronics giant’s attempt at serving developing nations: Bangladesh, Belarus and Bulgaria (to name three). It isn’t officially available in the USA or the UK and only recently appeared on €280 for the gold finish, €240 for the black.

    In a world of a thousand dollar flagship models we might assume Xiaomi have hacked back the A1’s hardware specs. You be the judge: 5.5” full HD screen; 3080mAh battery; 2GHz Octa-core Qualcomm Snapdragon 625 CPU; 4Gb RAM; 64Gb internal storage; twin lens 12MP 4K-capable rear camera; 5MP front camera; fingerprint sensor.

    On weight, the Mi A1 hits the pocket at 168g. On dimensions, it’s thinner and shorter than a Plus-sized iPhone but not as small as the standard Apple.

    The Mi A1 (further) diverges from the entry-level smartphone competition with band-limited dual SIM support. Where audio fiends win is with the second (nano) SIM card slot that can alternatively host a microSD card of up to 128Gb capacity. FLACs away, Ginger!

    Android has it all over iOS when it comes to remote file loading1. Here are three examples:

    Spotify and Tidal downloads don’t time out after periods of host device inactivity – we can queue up offlined content and let it run overnight.

    Application level access to the internal file system allows third party apps to fly in the face of Soundcloud T&Cs to offer one-click downloads of ALL streams (and not just those explicitly earmarked as such).

    Portal (and apps like it) invite us to scan a QR code displayed by a PC/Mac’s web browser for drag and drop wifi file uploading from desktop to smartphone.

    The Mi A1’s functional benefits don’t end with file loading. This is an Android One phone. It was co-developed by Google to offer pure Android and arrived devoid of Xiaomi’s divisive MiUI “Me You I” interface.

    In the final week of 2017, my Xiaomi Mi A1’s first boot was into Android 7.1.2 Nougat but queue jumped access to two years of major Android OS updates is part of the Android One proposition. The Mi A1’s Oreo 8.0.0 update came down the pike a few days later on New Year’s Eve. The immediate interest for yours truly was the promise of broader Bluetooth codec support. Enabling developer tools allows us to peak under the hood: Settings → System → About phone → tap ‘Build number’ seven (7) times → exit Settings.

    Returning to Settings → System newly exposes a ‘developer options’ panel that midway details Bluetooth connection options. At first blush it appears we can select from SBC, AAC, aptX, aptX HD and LDAC. Firing up the Sony MDR-1000X and hitting play on Spotify shows LDAC is in play – confirmed by the higher level Bluetooth settings panel – but selecting a different codec in developer options, even the Sony-supported aptX, does nothing to change this. We can tell the Mi A1 to engage ‘high-quality audio’ codecs but we don’t get to specify.

    Back in ‘developer options’, what we can specify is how the Mi A1 apportions the available Bluetooth bandwidth to the LDAC connection: optimised for connection stability (330kbps), audio quality (990kbps) or a combination of the two (606kbps). Selecting exclusively in favour of audio quality causes 10 seconds of stuttering before the connection settles to expose marginally greater evidence of surface textures and a slightly wider stereo image on Momus’ Pet Shop Boy-eque salute to the 1980s, Don’t Stop The Night – played via Spotify (Extreme). SQ deltas introduced by LDAC’s bandwidth allocation might be so small as to be of debatable benefit to this kind of music. What isn’t debatable is LDAC’s audible superiority to the same album spun from the same streaming service source but heard via the AAC-connected iPhone 6S Plus or the AAC-connected Mi A1 before its Oreo makeover. A win for this Sony-wielding porta-fi pragmatist.

    What about the B&W PX where LDAC isn’t part of the headphone deal?

    The bad news is that even with Dec 31st OS update installed to the Mi A1, the PX’s Bluetooth connection refuses to budge from the auto-negotiated AAC. Contrary to the initial Android fansite hoopla, Oreo doesn’t ink a Mi A1-centric license agreement between aptX owner Qualcomm and Xiaomi. When license fees are involved, the addition of aptX (HD) support to any given smartphone falls to more than software updates.

    The good news is the PX’s comparatively more abundant sense of transparency pulls the curtain back more resolutely on source quality changes. The audible delta between a Redbook FLAC played from a microSD card and Spotify 320kbps is more obvious.

    According to the Xiaomi website, Mi A1’s 3.5mm headphone output is good for high impedance cans. That remains untested by yours truly but for those who don’t find it to their liking, the USB-C charging port also doubles as digital audio output.

    The most obvious hook-up here is the AudioQuest Dragonfly Red – and not only because the USB dongle DAC’s red outer is a colour match for the SPAK smartphone case (€9 from The interceding USB-C to USB-A adapter, here made by Anker, feels quite a bit more robust than Apple’s own Lightning equivalent. And if the long haul says otherwise, a replacement can be snagged from for a measly €7.

    Less obvious is taking the Mi A1’s USB-C output to the B&W PX directly and losslessly, if not bit-perfectly. The DragonFly Red’s always-Magenta logo suggests the host Android OS is upsampling to everything 96kHz. A problem for idealists, perhaps, but less so for pragmatists who, when they hear the PX playing catch on a lossless digital signal will likely be stunned by the result. Such clarity and space!

    Hooked up to a Macbook Air running MacOS High Sierra, Audirvana+ reports the PX capable of receiving 44.1kHz and 48kHz which suggests some form of downsampling will take place once the Xiaomi smartphone’s 96kHz output hits the B&W headphone’s USB-C 48kHz-limited input. To fuss over such details runs the risk of glossing over the PX’s price-point wonderment: portable headphones, amplifier and DAC for €399.

    We should also pay strict attention to here is how the Xiaomi/AudioQuest pairing has all the functionality of the Sony NW-ZX2 – microSD card hosting, full streaming service functionality, LDAC Bluetooth streaming, USB output – but with a bigger/better screen, a more effortless UI, all for well under half the Sony DAP’s asking.

    The irony here isn’t lost on me: that the pursuit of better Bluetooth audio turned up a device that can also play hardwired, analogue and/or digital, into to downstream headphones. A device that seen alongside the Onkyo Granbeat and LG V30 – that offers aptX HD, an ESS DAC and MQA – has me convinced more than ever that Future-Fi in the portable audio space sits with the smartphone.

    For this Xiaomi and Google co-production, a KO Award for the Mi A1’s digital audio versatility and sky high performance/price quotient. Wired or wireless? Yes.

    Further information: Xiaomi

    Footnote #1: As with audio gear, so with computer hardware and operating systems: pragmatism before idealism. Throughout my day to day, I own/use a Microsoft Surface Pro, an Intel NUC, an Apple Macbook Air, an iPhone 6S Plus, a Google Nexus 5 smartphone, a Nokia Windows smartphone (I forget which model), an iPad Air 2, a Google Nexus 7 tablet and, now, the Xiaomi Mi A1 smartphone. This is information provided in order to head-off at the pass lazy accusations (from unthinking readers) of fanboi-ism in any one direction.

    Written by John

    John currently lives in Berlin where he creates videos and podcasts for Darko.Audio. He has previously contributed to 6moons, TONEAudio, AudioStream and Stereophile.

    Darko.Audio is a member of EISA.

    Follow John on YouTube or Instagram

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