6 Things to Look for in an Amplifier

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6 Things to Look for in an Amplifier

Those who wish to increase the power of an audio signal use amplifiers, and  are used in a variety of different situations. For example, there are amplifiers for car stereos, for record players, as well as those for large-scale PA systems.

There is a vast variety in the type and quality of amplifiers available on the market and this variety is represented in the price range that they are available for.

With this in mind, auction sites such as eBay offer potential buyers of amplifiers to purchase a higher quality amplifier at a more affordable rate.

This guide aims to take amplifier buyers through the seven fundamental things to look out for when purchasing one.

1.    Type of Amplifier

When buying an amplifier, one needs to know what type of amplifier is necessary before even beginning a search.

There are amplifiers available for many different purposes and settings. These individual types of amplifier are recommended to be used in a certain location, so as to get the best sound quality, as well as accounting for necessary size and weight.

There are amplifiers available on the market for the following purposes:

-   Hi Fi Stereo Amplifiers

-   Car Stereo Amplifiers

-   Personal Address (PA) System Amplifiers

-   AV Receivers (Television Amplifiers)

These types of amplifiers are only suitable for the purpose that they were built for. For example, using a lower powered car stereo amplifier is not suitable as a hi-fi amplifier, because the sound will be distorted. This is also the case in reverse, in that a higher-powered amplifier will not be suitable for use as an AV receiver.

2.    Amplifier Terminals

The terminals fitted in an amplifier can determine what can be played through it.

Knowing the input and output terminals of an amplifier can play a role in its versatility and ultimately its price.

There are a number of different terminals available on various amplifiers. This table details these inputs and outputs:

Amplifier Terminals


Headphone Output

A headphone output allows for the owner to listen to their audio through headphones. This may be done so as not to disturb those nearby, as well as to allow for a greater range of sounds and tones to be heard, especially if the speakers used alongside the amplifier are not sufficient. There are a number of different headphone output sizes.

The standard size for mid-range headphones is 3.5mm, but there are amplifiers available with 2.5mm headphone output sockets and larger. It is worth noting that there are specially designed ‘headphone amplifiers’ available for those who wish to solely use headphones whilst using an amplifier.

Auxiliary Input

An auxiliary input (aux) is designed for playing music from an mp3 player or phone through the amp. They come in a variety of forms, most commonly in the same size as a headphone output (3.5mm). If the owner of the amplifier wishes to play audio via an mp3 player, an auxiliary input is probably necessary.

Speaker Output

A speaker output allows for the amplifier to be played through speakers. Most amplifiers will have a left and right speaker output.

Line-In Input

Line-In inputs are designed more for higher-powered amplifiers and allow for the likes of microphones and smaller scale instruments to be played through them. 

3.    Power

The power of the amplifier is also an important thing to look out for when looking to purchase one.

The power plays a role in determining the quality of sound that comes through the speakers or headphones.

Amplifier power is usually measured in Watts (W) and there is a vast range of wattage available on the amplifier market. There are smaller car stereo amplifiers that are available at 10 to 20 Watts. However, there are extremely high-powered amplifiers that can reach up to 5000W in power.

Making sure the right wattage of amplifier is acquired is important, as an amplifier that is not powerful enough to play audio at high volumes may mean that sounds are distorted and the quality of sound is poor.

4.    Heat Sink

Higher-powered amplifiers will heat up due to the energy that is created whilst in use.

For this reason, it is important that an amplifier has a heat sink fitted as part of the design. Whilst most amplifiers will have one as standard, there is also the opportunity to purchase cooling equipment to prevent the amplifier from overheating.

To find out whether an amplifier has heat-sinking equipment fitted, either check the product description or study the images of the amplifier. Usually an amplifier will have thin ridges at the back or on the sides, which is an indication of heat releasing technology.

5.    Aesthetics

For many amplifier owners, the way that an amplifier looks is an important part of the buying process.

With the likes of car stereo amplifiers, looks may not be as important as they are often hidden behind upholstery. Furthermore, the likes of PA amplifiers do not tend to come in a variety of styles and designs as for this type of amplifier; style is less of a priority than functionality and performance.

However, for AV receivers and hi-fi stereo amplifiers, the aesthetics of the amplifier is fundamental to the choice that is being made. Most amplifiers will be made from metal, due to the heat that is created during use, although some are available in durable plastics.

For those looking to create a modern look for a home stereo system, be sure to match the colour of the amplifier with the speakers being used. A lot of amplifiers are designed in black or silver due to the materials that are used in their manufacturing.

6.    Dimensions

When buying an amplifier, it may be an idea to take note of the space available for it to be placed it before settling for a purchase.

With amplifiers coming in a range of different sizes, it is important to know this, so as to avoid spatial and heating issues.

The following dimensions measure most amplifiers:

-   Width

-   Depth

-   Height

Therefore, the numbers given for the size of an amplifier will be in this order. For example, an amplifier noted as being 430 x 340 x 80 will be 430mm in width, 340mm in depth and will stand at 80mm tall.

It is especially important to take note of the size of an amplifier if it is being used for car stereo purposes, as space can be more of an issue in this instance.

Buying an Amplifier on eBay

eBay is a cost-effective resource for finding the likes of amplifiers at affordable prices that may not be able to found elsewhere.

The first step to purchasing an amplifier from the site is to check the Deals section, an area of eBay that handpicks bargains from its electronic listings.

One can also visit the Electronics category of the site before clicking the Audio link and choosing the Amplifiers refinement tab. From here, one can view the thousands of listings of amplifiers on the site. Furthermore, one can make use of the various other filter tabs at the side of page to make the search as specific and accurate as possible.

Once an amplifier has been found, be sure to thoroughly read the specifications that should be included in the product description, as well as checking the seller’s previous transaction history. More often than not, sellers can be contacted directly if any questions or issues arise.

Finally, be sure to understand the ins and outs of using the Buy It Now, Bidding and Best Offer buying options before using PayPal to complete the transaction.


Therefore, there are six fundamental things to look for in an amplifier when planning to purchase one.

Be sure to check its dimensions to make sure it fits in the desired space, as well as making sure its design is not too overbearing or out of place.

Furthermore, from a technical perspective, make sure to purchase an amplifier that is of a sufficient and suitable power, as well as one that has all the necessary inputs and outputs.

With all this in mind, an amplifier can be purchased on eBay that is appropriate for its intended use, via an affordable and secure transaction.

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