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Headphones are more popular now than ever before because of the exceptional audio they produce, especially headphones with high impedance ratings. However, they are not without their caveats. Let’s take a look at high impedance headphones (specifically 250-ohm headphones) and what these caveats could be like requiring an amplifier to run them.
You can technically use 250-ohm headphones without an amplifier; however, the audio that is produced will be sub-par to what they are designed for, outputting a meager volume (if any volume at all), having distortion in low frequencies, and being muddy. Hence amplification in some form is recommended for 250 ohm headphones.
If you are looking to purchase a pair of high-quality 250-ohm headphones and wondering if you will have to spend additional cash on an amplifier to power them, then this article is a must-read. By looking at headphone impedance and their sensitivity/efficiency rating, we will determine if high impedance headphones really do require an amplifier.
Can you use 250-ohm headphones without an amp?
So let’s get straight to the facts, the short answer is that yes, you are able to use your 250-ohm headphones without an amplifier, they will play sound. In fact, I quite often use my Beyerdynamic 990 pros (pictured above) just plugged into my phone or laptop and sound does still come out.
However, specially designed audio-production headphones that have an impedance level of 50-ohms and above are specifically designed to produce high-quality sound, and as such, they need a particular amount of current and power to drive them.
Not having the correct current and power will result in your headphones producing a sound that is quieter than you might like, potentially muddy, and even slightly distorted in the low-frequency range.
Therefore using an amp with headphones that have an impedance level of 50-ohms or higher is always recommended, even if not essential.
It would help if you consider that headphones with high impedances typically cost a lot of money, and if you do not use them with an amplifier, then they will not sound good enough to justify their cost. Treat that kit with respoect!
Understanding headphones and impedance
As we stated, nicer headphones (ones that offer high-quality audio) are typically ones that will have higher impedances of 50-ohms or more. Impedance is a measurement used to determine how much something can resist an electrical current and is measured in ohms.
Without going into too much detail about impedance, you will only need to understand that headphones built with high impedances (in our case, 250 ohms) will result in much better audio quality. Headphones or earphones that are designed to be compatible with your portable devices (laptops, smartphones, etc.) are designed with low impedance levels (typically 35-ohms or less) and thus do not require an amplifier to drive them.
How to select a suitable amplifier for 250-ohm headphones
Knowing that your headphones are 250-ohms is the first step. The next step is to determine what efficiency rating they have.
The efficiency rating is a measurement that tells us how many decibels the headphones will output per milliwatt or millivolt. You can typically find this on the packaging that the headphones come in or in the owner’s manual. If this measurement is not given for some reason, you will only need to search online for this measurement.
Take note that headphones can have a sensitivity rating or efficiency rating. These are both considered the same; however, sensitivity is measured in volts while efficiency is measured in milliwatts.
Once you have either the sensitivity/efficiency rating of your headphones along with the impedance value (in our case 250-ohms), you can then input that information into an online “headphone power calculator.”. You can find these calculators free online with a quick search, and here is one for your per usual.
The result will show you how many milliwatts you will need to get your headphones up to a specific level of loudness. A good rule of thumb is to assume you need a maximum level of 110dB. This is approximately 10dB lower than the threshold of pain for humans.
Once you have this number, then all you need to do is to check if the amplifier you are considering is at least that high.
For example, let’s take Beyerdynamics DT 990 Pro headphones. These headphones have an impedance of 250-ohms and an efficiency rating (power handling capacity is heading under which you will find this in the manual) of 100 milliwatts.
Punching these two values into our online power headphone calculator, we can see that for 110dBs; we will need at least an amplifier that can output 9.99 mW (milliwatts).
Many amplifier spec sheets will give you a detailed description of how much power the amplifier can produce for specific amounts of ohms. This will give you a better idea of how much power your amplifier can produce when used with headphones of different impedance levels.
It may also be a good idea to get an amplifier that is a little bit stronger than what you need because many headphones can have varying impedance levels depending on the frequencies of sound involved.
For example, Seinheiser makes top-rated headphones known to have impedance spikes in the lower frequency ranges. This means that you will need to check impedance graphs for headphones online to see the peak impedance level among the frequency ranges for the headphones you have or like.
Take note that these impedance graphs will be widely available because, for the most part, if you have or are looking to purchase 250-ohm headphones, chances are they are a name-brand and are pretty good. Hence lots of information (including the impedance graph and specs) will be available online.
The last factor you will need to consider when purchasing an amplifier is its output impedance rating. You want to make sure that your amplifier’s output impedance is at least 8 times lower than the impedance of your headphones.
In our case, we have 250-ohm headphones, which means that we will need an amplifier that outputs around 31-ohms.
Does an audio interface have a headphone amplifier built in?
The majority of you reading this are probably looking to use your headphones for audio production, and in that case, you are likely to already have. or about to have an audio interface. This small (or sometimes large box) allows you to convert audio signals from various instruments and microphones and convert them into digital signals for your computer to understand.
The good news is the vast majority of audio interfaces do have headphone amplifiers built-in. Of course, the quality of these amplifiers does vary and you aren’t going to get a high-end amplifier in an all-in-one interface packager for under $200. But for the majority of producers, at least those starting out, the amplifier in the interface will do a fine job.
If you already own an interface try mixing with your headphones plugged into it and if it doesn’t sound great try a headphone amplifier.
The great thing these days with online returns is that you can always send it back if it again doesn’t make a noticeable difference to the sound.
Will using my 250-ohm headphones without an amp damage them?
You will not damage your 250-ohm headphones if you use them without an amplifier. However, as we stated, the audio produced is inadequate and will not be worth the investment of your headphones.
Recommended Headphone Amplifier
If you’re looking for an entry-level headphone amplifier to get a bit more sound quality out of those 250ohm headphones then I thoroughly recommend the Mackie HM series. Great value and more importantly built like a tank so you can throw them in a bag, take them on tour and they should last a long time
Gone are the days where headphones are just simple devices that you can plug into your audio system that will reproduce sound. Headphones now come with varying impedance levels creating much higher quality audio, even being used in the recording studio for mixing and mastering.
Understand that plugging high impedance headphones straight into a device without amplification will result in audio that is less than optimal, if it will even play at all. This is because headphones with an impedance rating of 50-ohms or more will require a significant amount of power to drive them properly, and this will come from an amplifier.
While you’re here, you may like our guide on if you need an amp for 80 Ohm headphones.