I got aptX on iPhone with this device, and it made a big difference

Apple refuses to support other Bluetooth standards that increase the amount of data transferred to audio devices such as earbuds and headphones. Why is this a problem? This is because Apple only uses the AAC Bluetooth codec, which is limited to 250 kbps, compared to Sony’s LDAC, which has a maximum of 990 kbps. This means that most AirPods cannot transmit enough information to provide the best audio experience. However, there are ways to bypass the limitation of only having AAC on iPhone.

That’s where the Questyle QCC Pro can come in to add support for higher-bitrate codecs, such as aptX Lossless and LDAC, for your iPhone. It even features support for Snapdragon sound, which is not yet supported by many Android smartphones. Of course, the real question is, does it make a meaningful difference worth spending $100 for?

Does a higher data rate matter?

Newer sets of earbuds now offer a wide range of codecs to choose from. LDAC, as I mentioned, has a maximum data rate of 990 kbps, and you are likely to find many earbuds, even in the mid-range price point, that support it. Another codec gaining significant support is aptX lossless, which operates at a data rate of up to 1,200 kbps, achieving CD-quality sound data rates. Still, none of Apple’s devices support either.

Even if you’ve purchased the latest AirPods Pro 3 to pair with the latest iPhone 17, you’re still limited to the lower-bitrate AAC codec for audio. You would think Apple would finally catch up with the times and start supporting higher data rates. But Apple doesn’t believe that this is a requirement, and they’re right for the most part. The AAC codec uses psychoacoustic modeling—compressing data based on human perception of sound—which makes it punch above its weight class.

Despite AAC’s efficiency, it consumes more processing power than most other codecs. Thankfully, modern smartphones have enough processing power to make this negligible. This means Apple shouldn’t have a processing power issue. So, with a device like the QCC Dongle Pro, which provides access to LDAC and aptX, does it make a significant difference?

Does it actually make a difference in sound?

To find the difference using the Questyle QCC Dongle Pro, I alternated between the ifi GO Pod Max connected to the IE 600 wired IEMs. Moving between connecting to the Questyle QCC Dongle Pro on aptX adaptive in high quality mode, disconnecting, and reconnecting to an iPhone 17 with AAC.

I have used the IE 600 for a long time, and I’m familiar with how it sounds. It is also one of the few IEMs that I daily drive, which is close to the SoundGuys’ preference curve. The iFi GO Pod Max was used, as it supports aptX lossless and AAC, while allowing me to adapt my wired IEMs to wireless.

aptX and AAC compared side by side

The direct AAC connection to the iPhone sounded considerably more compressed. A lot of the subtler sounds are much louder. For some people, this may be a good thing. For others, it may be distracting and ruin immersion. It’s the difference between hearing the chirping of birds in the background and hearing it come from an arm’s length away, despite the bird being small and distant. The compression isn’t drastic, but easily noticeable. For most people, louder sounds are much more appealing.

I find that on AAC, the upper treble is slightly underemphasized. The upper treble is mostly responsible for the sense of space. The underemphasis can make the perception of spatial depth smaller, as I noticed on the track “Never Fear” by Mao Abe. It also makes the high-pitched metal instruments in the track, such as cymbals, sound a little unnatural. Going through aptX, cymbals sound noticeably more natural. The sense of spaciousness is also improved a bit.

Mids on AAC lack some clarity. Vocals tend to get a little more lost in the mix, just enough to notice in the track “Sepia” by Mori Calliope and TOOBOE. Trying to isolate just the vocals during busy sections of a track was a little difficult. Moving to aptX, I was able to get a decent bit of separation from the instruments and vocals. It’s much easier to isolate a single instrument.

When trying to find differences in the bass, I couldn’t easily perceive any differences. Moving between LDAC and AAC, and testing with tracks that I’m familiar with, like “Bloodstream” by Neoni or “Fallout” by LeGrand. I wasn’t too confident to say that there was a noticeable difference between AAC and aptX.

Overall, using aptX is an improvement over AAC. But is it really worth paying $100 for?

What is it like to use the Questyle QCC Dongle Pro?

The Questyle QCC is designed for iOS devices, such as the iPhone and iPad. You can still use it with Android devices, as well as desktop computers running Windows or macOS. With the dongle, you can access LDAC, aptX, and Snapdragon Sound, even if you’re using an iPhone. The downside is that you’ll have to use the USB-C port on the iPhone and pair it with something that supports a higher bitrate codec. Sorry, the AirPods Pro 3 isn’t one of them.

Questyle mobile app

The Questyle app is where you can manage the connections. To my surprise, there is a game mode that also enables compatibility with consoles. This includes the PlayStation 4 and 5, as well as the Switch 2. We didn’t test console gaming for this review, but the feature is there if you need it. I would advise setting the connection mode to low latency before doing so. However, the latency is also affected by what you connect to the dongle.

In the app, I can see the list of devices I’ve connected to and remove them from the list. This is just like using the Bluetooth device manager on most smartphones. Unfortunately, there are no additional features, but it does provide a wired connection. This means that any EQ adjustments made on the device will affect the sound of your connected device.

To ensure the best sound quality, adjust the connection settings. You can prioritize either connection or sound quality. Be aware that prioritizing sound quality can lead to more connection dropouts. This is because some data can be lost along the way. Although at that point, you can just use AAC, as it’s more than close enough and has decent sound quality.

What I like about the QCC Dongle Pro

Lossless audio sounds considerably better to my ears. For most people, it would be nice to have something much better, but it isn’t a complete game-changer. I see the best use case for the higher data rate in a quiet environment, such as at home. I was able to use the QCC Dongle Pro to achieve a significantly improved listening experience on a Mac. I enjoy maintaining better audio quality while being able to move around. This made it much easier to relax as I didn’t have to worry about wires. I was also able to use the playback controls and microphones of the earbuds.

I don’t see the lower bitrate being an issue in the use case when you’re out and about with an iPhone. Chances are, you won’t be using it for critical listening a majority of the time. It’s perfect for listening to a podcast or music during your commute. That means you will likely be in the vicinity of things like the screeching of train tracks, the honking of cars, and the wailing of children. Maybe that last one you even hear at home.

What I don’t like about the QCC Dongle Pro

Using the Questyle Dongle Pro isn’t without its issues. The body of the dongle is wider than I would like. This doesn’t always pose an issue, but it can block adjacent ports as it’s slightly wider than a USB-A port. A USB-C to USB-A adapter is included, allowing you to connect to more devices. When connected to a phone, the USB port being blocked also means you’re stuck to using wireless charging.

The biggest problem with the QCC Dongle Pro is that it frequently disconnects during my commutes. When walking with the phone and receiver in my pocket, it would constantly disconnect. The audio would intermittently cut out on one ear or the other. However, when I hold it in my hand while walking, or just sitting during a commute, there are no connectivity issues. When laying it on the table, it’s fine. However, that defeats the purpose of having a portable dongle that you can connect to your phone.

Chances are, the disconnects are mostly because of the dongle getting pushed around and disconnecting just enough to cause issues. It might also be because it’s unable to push the wireless signal through objects, including my own body. I occasionally experience issues with Bluetooth connections, even with standard earbuds like the AZ-100. Again, even though it is connecting through a portable dongle, its best use case is in a stable environment.

A better listening experience doesn’t really matter for most people running an iPhone. Maybe it did back when Apple still made the iPod; they still cared about audio. However, the iPhone is now the do-it-all experience. It doesn’t require LDAC, aptX, or a higher-bitrate codec for audio. It would be nice to have, and I would gladly welcome the change. It’s great for those times when I do use the iPhone like a portable audio player.

Should you buy it?

Buy the Questyle QCC Dongle Pro if you’re a home listener with high-bitrate FLAC files and earbuds that support aptX or LDAC. In that context, it’s excellent—there’s more detail and spaciousness in the audio, which makes it a much more immersive experience. You have access to higher-quality FLAC files, which can reach up to 1,400 kbps, utilizing higher-quality codecs like aptX lossless, which can achieve up to 1,200 kbps. Even if you’re using the more common LDAC codec at 990 kbps, it’s still superior to AAC at 250 kbps. If you want to make the most of earbuds like the Sony WF-1000XM5 on an iPhone, the QCC Dongle Pro unlocks their full LDAC potential at home.

Skip the QCC Dongle Pro if you want portable use. If you’re thinking of taking it on a jog or workout, you’ll have to hold on to your phone. Otherwise, it’s prone to a lot of disconnects when shoved into a pocket. All that jostling is likely to push on the dongle and cause the audio to cut in and out. At that point, connecting to AAC isn’t as bad, even at the lower data rate of 250Kbps. In the context of being in a noisy environment, you aren’t going to be able to listen closely to all the little details in a track anyway.

If the QCC Dongle Pro’s portability issues are a dealbreaker, consider alternatives. The regular QCC dongle (without “Pro”) still supports aptX Lossless and costs less, though you’ll lose LDAC support. Alternatively, some headphones like the Sennheiser HDB 630 come with their own aptX dongle, eliminating the need for a separate adapter.

QCC Dongle Pro review: FAQs