After performing a series of tests on the device’s headphone jack, Mashable has confirmed that the new iPhone 6 doesn’t play high-res sound or HD audio. To test the iPhone 6’s high-res audio capabilities, various test tones with a 96kHz sampling rate and 24 bits per sample in .wav format were played from the iPhone’s headphone jack to a high-res audio recorder running at a 96kHz sampling rate, 24 bits per sample.
The recordings were viewed in Adobe Audition desktop audio-editing software and compared with the “raw” signals from the original files. According to audio-testing expert David Ranada, the results showed that the iPhone 6 does not play high-res audio, at least not yet. However, the source notes that it’s likely that the limitation has more to do with software than hardware.
“The digital-to-analog converter (DAC) — the piece of hardware that actually converts those digital bits into music — is the Cirrus Logic 338S1201 chip, according to teardowns. That chip is custom-built for Apple, so its specifications aren’t public. In previous generations, the chip was the Cirrus Logic CS42L61 — also a custom job, but part of the company’s CD42L range. The last chip in that range was the CS42L51, which is capable of sampling audio up to 24-bit/96kHz.
It’s hard to conceive of Apple either creating a custom chip that’s less capable than the equivalent off-the-shelf component, let alone downgrading the audio capabilities of the iPhone’s DAC in subsequent generations. So it stands to reason the DAC on board the iPhone 6 is capable of sampling 24-bit/96kHz audio”.
So, it appears that Apple limits the iPhone’s playback sampling to something closer to CD quality, most likely to ensure better battery life for music playback, which it rates at up to 50 hours on the iPhone 6 and up to 80 hours on the iPhone 6 Plus.