The rule that I use is that the bigger the size of the headphone, the bigger the need for amplification. Of course factors like driver sensitivity and impedance will matter, but the general rule of thumb is, use a dedicated headphone amplifier for a full size headphone. Even a portable amplifier can be enough, depending on the type of the headphones.
Alternatively, online calculators can be used. Once the sensitivity per volt is known, the maximum volume for a pair of headphones can be easily calculated from the maximum amplifier output voltage. For example, for a headphone with a sensitivity of 100 dB (SPL)/V, an amplifier with an output of 1 root mean square (RMS) voltage produces a maximum volume of 100 dB.
While iPhone users can expect that their phones are missing essential parts to look good, AAC is one of those codecs that maybe cut a few too many bits out of its data transmission. By using an aggressive psychoacoustic model of compression, AAC seeks to cut data where you wouldn’t normally be able to hear it anyway—but it gets a little too aggressive at times.
If you just want to block out sound without active noise cancellation, good over-ear headphones will naturally do that to some extent. This is called noise isolation, and it simply works from the earcups forming a good seal over your ears to prevent outside noise from getting in. It's not as effective, but it's less expensive than active noise cancellation and doesn't require power.
I’ve never enjoyed the audio quality of Bluetooth headphones, but that’s just me. The sound is better than it ever has been, and it’ll get you 90% of the way there—but not everybody is willing to make that tradeoff. Since USB-C headphones have largely ceded their market advantages over Bluetooth, we have to examine the consumer audio technology’s performance in a world where the headphone jack is disappearing.
Over-ear and on-ear headphones effectively block out outside sounds, allowing you to hear your music or whatever else you're listening to crisply and without distraction. Over-ear headphones are sometimes known as full-size headphones because they completely envelop the wearer's ear. This results in what's known as passive noise reduction, which makes these some of the most-preferred headphones available. The only drawback is that your ears and the skin around your ears can get warm and sweaty. These are usually the heaviest type of headphones.