By one way or another, we have been acknowledged that many users are haunted with one question: which FiiO amplifier would go perfectly with one certain headphone or earplug.

Generally speaking, we should take the timbre and the power into consideration when speaking of the match of amplifier with headphone. As is known to us all, the match of timbre is kind of complicated. For those who possess headphone in somewhat “cold sound”, all he needs is a “warm sound” amplifier to balance it out. Due to the subjectivity of timbre, it can’t be quantized or described with specific numeral data which then results in” Each one thinks in his way.”Therefore, here we may mainly focus on the explanation on the matching from the aspect of the power.

First of all, we should have a clear definition here. In term of the sound reduction merely, different people would have different expectations of the sound according to different using environment, personalized listening curve and individualized loved music type. Therefore, we need to do a simple classification regarding the headphone sound.

**A. Standard sound pressure (95dB):** Under normal application environment, we define the sound pressure of the headphone as standard level when enjoying popular music. Considering the theoretic dynamic range of CD being 96dB, whereas the minimum sound pressure that human ear can hear out of 1 KHz is 0 dB, then the dynamic range for the maximum sound pressure of 95dB is 95dB as well. As a result, we define the maximum sound pressure of 95dB as the basic needs of enjoying common music.

**B. Favorable sound pressure** **(105dB):** As a matter of fact, 95dB sound pressure is far from satisfactory in enjoying high quality music. Normally speaking, in terms of the live show of symphonic music, rock concert and other sort of high dynamic music forms, the maximum sound pressure can reach 105dB. Therefore, we define 105dB sound pressure as favorable sound pressure.

**C. Excellent sound pressure (120dB):** 105dB sound pressure, is it enough? In reality, the sound of the nature is far above 105dB, like the sound of the thunderstorm, the sound felt towards a plane flying nearby whose maximum sound would hit above 120dB. Also, the record of SACD format music can reach 120dB as well. That’s why we regard 120dB as excellent sound pressure.

With the help of this quantized sound pressure levels, we can calculate how much power it needs to boost one specific headphone according to the theoretical computational formula.

The procedure and formula of the calculation are as follows:

**1.** Usually, each headphone would be given with one sensitivity data which is tested under the environment of below 1mW power.

**2.** Based on the required sound pressure, work out the corresponding power (P for short).

Assuming the maximum required sound pressure as B, and A as the rated sensitivity of the headphone, then the computational formula would be P=10^ ((B-A)/10).

**3.** In line with the power requirements, figure out the required maximum voltage and current.

The reason why we should calculate the maximum voltage and current is because P=I（current）*U（voltage）.

As to the fixed output power of one certain amplifier, it may thanks to the high output voltage or because of the high output current.

Take the Beyerdynamic DT990 for example, while in different headphone impedance with one version at 32Ohm and one at 250Ohm, in order to get 120dB sound pressure, they both require for 251.19mW power due to the same sensitivity. However, the required maximum current of the 32Ohm version is 88.60mA which is far above the 31.70mA of the version with 250Ohm.

To the contrary, the demanded amplitude peak in boosting the voltage of the DT990 with 250Omh impedance would be 22.41V which is far above the 8.02V of the version with 32Ohm. This tells us that power rate is not the only thing we should consider. To a headphone with low impedance, high current and low voltage is what it requires, while high voltage and low current would be the target of headphone at high impedance. That’s why we need to work out the corresponding output voltage and current in order to select suitable amplifier.

One more thing we need to be aware of is that the impedance and the sensitivity of the headphone is not a fixed figure which might vary with the headphone input signal’s response. Generally speaking, the maximum impedance of the headphone is higher than the rated one, which even can be 3 folds higher. So does the minimum impedance and the rated one. Thus, the data result from the formula should be regarded as a merely reference.

To sum up, in accordance with corresponding power and high dynamic peak voltage required by 120dB sound pressure and the current demanded by high dynamic, the chosen amplifier would basically meet some kind of high level of sound effect. If take the power storage into consideration, we can also get it doubled or tripled based on the related power of 120dB.

You can feel free to visit our official website at www.fiio.net to get the related information about the maximum output power, peak voltage of high dynamic and the current of high dynamic in terms of all the amplifiers and amplifiers with decode function. You are warmly welcome to select the suitable amplifier to your own headphone based on the listed information.

Based on this formula, we have worked out the power, voltage and current for some popular headphones.

In order to get the best sound effect, you can refer to the power required by 120dB sound pressure and peak voltage required by high dynamic.