The WH-1000xM3’s advanced control systems allow you to let in various levels of ambient sound, with advanced features like voice-only mode, which helps filter through vocal frequencies so you can hear your music and the voices around you while blocking out other sounds. Responsive touch controls let you navigate volume, make calls, and play and pause music with ease, all while helping to maintain a clean aesthetic. Best of all, the WH-1000xM3 offer a staggering 30 hours of battery life, providing even heavy users with days of use from a single charge, and have a quick charge feature that allows you to enjoy five hours of listening after just 15 minutes of charging.
We use a commercially-available Bluetooth high-def interface with an S/PDIF output to test the Bluetooth output of four flagship phones. This way, we’re able to record test signal output and compare the datasets with our in-house analysis software. We kicked the tires on a 96kHz/24-bit test file to see how Bluetooth handled high-bitrate music, as well as normal 44.1kHz/16-bit files to see how each codec treated CD-quality streaming audio. We then measured the recorded sample against the original file. We used both lograrithmic sine sweeps, and complex signals like square waves in order to provide a more realistic set of tests for how people actually use Bluetooth headphones.

Today they are typically used only in in-ear headphones and hearing aids, where their high efficiency and diminutive size is a major advantage.[20] They generally are limited at the extremes of the hearing spectrum (e.g. below 20 Hz and above 16 kHz) and require a better seal than other types of drivers to deliver their full potential. Higher-end models may employ multiple armature drivers, dividing the frequency ranges between them using a passive crossover network. A few combine an armature driver with a small moving-coil driver for increased bass output.

The iPhone will drive the headphone fine and make a very nice sound, but the amp will make a big improvement in harmonic extension and soundstage. Use the amp whenever possible. Both Headfonia and I concur that the E07k is a great amp, and probably the best thing you can get for up to twice the price. I’m familiar only with the E07k, the E17, and the E12. I think the E07k beats the E17 (and both are also USB DACs), while the E12 is just an amp, and has a darker sound but with more power for inefficient headphones. The Philips is not inefficient.
Earbuds have small speakers that rest on the ear canal of the wearer. These are usually much less expensive than on-ear and over-ear headphones and reproduce the sound well. However, outside sounds, such as traffic or power tools, can get past the earbuds and interfere with your enjoyment. Earbuds also don't stay in place very well if the wearer is moving much, such as exercising. These also are lower fidelity than on-ear and over-ear headphones.