Any smart phone or portable music player will have an amplifier built in but the way you will determine whether you will need an external standalone unit is whether you will see an improvement in sound quality over that standard inbuilt amp. If you looking to move up a notch in musical performance. If you want spent more headphones and spent more money than normal ones, and the best quality sound experience .you may want to consider the headphones with amplifier. Choosing the best headphones amplifier is not a tough task however, one that involves a bit of understanding and knowhow about what works best as per your requirement.
The ways to look for better headphone amplifier are.
Headphones with higher impedance (25 ohms and over, approximately) demand more power to deliver high audio levels. Not that anything catastrophic will occur with an impedance mismatch, but you might not get the best sound quality from a headphone with impedance that’s too high or too low for your music player or home amplifier.
Low-impedance (under 50 ohm) headphones will play well at home with your receiver and on-the-go with your smart phone, and that’s why the clear majority of in-, on-, and over-the-ear headphones are low-impedance designs. High-impedance models are much better suited to home
High-impedance cans will usually need more voltage to get up to a solid listening level, so they can benefit from a headphone amp especially with portable players that have limited voltage available from their internal batteries. But very low-impedance cans lower the damping factor between the amp and headphones and require more current. So, while low-impedance headphones may be plenty loud enough from a portable device, sound quality may be significantly improved using a headphone amp in this instance as well. Choose the best headphones amplifier here.
Sensitivity indicates how loud the earphones will be for a given level from the source.
Important factor is that of the sensitivity this is one of the easiest ways to determine if your headphones or earphones will benefit from amping.
Sensitivity ratings are commonly shown as DB (Decibels) levels per1mw (Milli watt) of power supplied. Typically, anything over 100DB at 1mw will be driven sufficiently to ample volume without the need for an external amplifier.
If a headphone spec includes very high frequencies above 23,000Hz, that’s a good sign, and the headphone might sound clearer than a headphone with a 18,000Hz spec.
Low frequency response with closed-back, full-size, and in-ear headphones, the best bass is only achievable when the earpieces have an airtight seal. Unfortunately, when head shape, eyeglasses or hair compromise the seal, bass suffers. The less perfect the seal, the greater the bass losses.
Benefits from using a headphone AMPLIFIER
Some amps come with various connectors that may be of use to oneself. Another benefit many people like is the fact that an amplifier can often provide a physical volume control that will allow you to make very precise adjustments to volume. Similarly, some amplifiers offer features that allow you to physically alter the sound.