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Apple’s iPhone is pretty well known to offer excellent sound quality through its analog outputs that is head and shoulders above the competition. Apple has been using Wolfson chipsets from the very beginning but later moved to Cirrus Logic chipsets – pretty good choices for a mobile device. The sound quality is actually more than decent at full volume level. A simple 3.5mm to RCA cable is all it takes to hook up your iDevice to your stereo system. But you CAN get way better sound quality by using an external DAC!
Why use an external DAC?
My plan is to use my favorite apps including Qobuz, Tidal and Apple Music with the hope of the sound quality being good enough for my main rig. Of course being an audiophile, I kept wondering whether I could outperform Apple’s built-in DAC chip.
I’m also tired of paying boatloads of cash for “audiophile” specialist software like Roon or Audirvana just to get a good digital output signal. After all, why do I have to pay when the native apps already output full high-res material, right? Don’t get me wrong, I really love Roon (also still have an Audirvana license as backup – although I refuse to go with their subscription plan) and will probably continue using it. But I just don’t see the value when I’m mostly streamig these days and rarely go back to my local library. Heck, more than 95% of my CD collection is available “in the cloud” anyway, so why bother setting up complicated streaming servers when Qobuz does the trick?
With the advent of iOS 7, Apple has officially announced support for streaming digital audio. That’s great news because it means you can practically take any iDevice running iOS 7 or later – this includes iPads, iPhones or iPod Touches – and connect an external DAC (digital-to-audio converter) with USB input. There’s a limitation of bitrate however so you are not going to be able to play high-resolution 24bit tracks directly.
What You Need
Self-powered USB DAC with optional USB hub
A self-powered USB DAC is an ideal starting point. Self-powered means your DAC won’t draw additional power from the USB port. This is important because Apple intentionally limits the power consumption by software to about 5mA. If however your DAC does rely on USB power or if it declares itself as more power-hungry than Apple allows upon connecting, you are going to need a powered USB hub. Apple will alert you so don’t worry – you can’t break anything.
I personally use a cheap powered USB hub from SIGMA which unfortunately is no longer available. You can typically find USB hubs for less than 20 bucks on Amazon.com (advertisement). Of course this means you have to manage yet another device but it’s a minor pain compared to larger music server projects.
If your DAC provides self-powered USB ports, however such as my RME ADi2 DAC (my Gustard X20 has it, too) you won’t need a USB hub. I suggest you try.
Next, you need an adapter for your iOS device that provides a USB output. Here’s where things differ slightly depending on your iOS device generation:
iPhone with 30-PIN connector:
You are going to need Apple’s 30-pin Camera Connection Kit (CCK) adapter (part number MC531ZM/A) (advertisement) and take the USB output to your DAC. More on that below.
iPhone with Apple Lightning connector:
Newer generation iOS devices including the iPhone 6 require Apple’s Lightning to USB Camera Adapter (part number MD821ZM) (advertisement). Again, connect your DAC from the USB output of the adapter.
I personally didn’t want to spend big money on Apple’s adapters and I bought this instead (advertisement link) which works really great and costs only half as much. I haven’t tested other features of this adapter but for USB audio it works great.
1.5ft USB 2.0 cable
Just about any standard USB cable will do the job. Nothing fancy needed here. Use what you have or purchase on from Amazon.com (advertisement)
How To Set It Up
First, connect Apple’s dongle to your iDevice and plug the USB cable into the provided USB port. Hook up the other end of the USB cable to your powered USB hub’s input. Finally, take the USB connection from your DAC to one of the ports of your USB hub – I use the first port for simplicity. You should now be able to play back music from your iPhone through your external DAC.
My Personal Setup in the Past (2017)
I use my company’s iPhone 4S hooked up to a JDS Labs ODAC (advertisement)
for experimenting purposes. As you can see, Apple’s CCK output goes straight into my USB hub’s input port. My external DAC does not have its own power source so the wiring is a bit messy.
My Current Personal Setup (2021)
I use my trusty 2018 iPad as a streaming source. Simply plug in the lightning cable and connect a short USB cable to the other end. Plug that into your DACs USB input. Done! All sound will automatically be routed through your external DAC. I was super-surprised to see that my iPas was capable of streaming not only 24/192 high res tracks from Qobuz but also DSD!
I can hear a small audible improvement with lossless tracks, maybe a bit more air around the instruments. It’s hard to say because the volume levels need to be matched precisely. At the end of the day audio is subjective anyway and while your external DAC may be technically superior to what Apple offers, you may or may not hear sonic improvements on your setup. But for music afficionados seeking the best possible performance, I definitely recommend going with an external DAC as above. At least give it a try.
A problem with USB audio however is the actual clock reconstruction method leading to higher levels of jitter. Taking a digital signal to an external DAC can also introduce all sorts of nasty noise problems that can interfere with the audio signal.
Is this for you? I have been using this setup for 4 years now and I totally recommend going with an external DAC NOT ONLY if you are traveling and want to squeeze out a tiny bit of extra performance for your mobile listening enjoyment but for actual HOME USE. For stationary listening, I would even say that you don’t need any expensive streamers anymore. I would peronally rather use my iPhone or iPad as a remote control device than becoming the sole source of music but I currently use my Apple Watch to control playback! This is the most overlooked solution these days for streaming audio.