How to Buy Integrated Amplifiers

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How to Buy Integrated Amplifiers

An integrated amplifier is a combination of a preamplifier and a power amplifier in one single unit instead of having two separate units. The preamplifier, also called the preamp, is used to prepare the small incoming electrical signal for further processing and amplification. The power amplifier is the main device used to increase the signal power by using an external energy source.

Most contemporary amplifiers are integrated to save space. They also generally have multiple inputs to accommodate various audio sources, such as DVD players, CD players, Blu-ray players, and various MP3 devices. Some vintage integrated amplifiers also have inputs for older devices, such as tape recorders, turntables, and tuners. All the devices use the same line level input with the exception of the turntable, which also use RIAA equalization.

Buyers need to choose the right integrated amplifiers for their audio systems because it can dramatically affect how the system sounds. They need to consider the various integrated features, the power per channel, and amplifier classes before making a final decision.

What to Expect from an Integrated Amplifier

Before buyers venture out to buy an integrated amplifier, they need to be absolutely certain that an integrated amplifier is what they need. In essence, they should be aware of the various advantages to buying one as well as the disadvantages that may affect their decisions.

Advantages of an Integrated Amplifier

Because an integrated amplifier combines the preamp and the power amp on the same chassis, it minimises the complexity of the stereo system and diminishes the need for RCA cables. The cables would have normally been needed to connect both amps when they are separate. This combination factor also reduces the price, simply because it is cheaper to use one chassis for both amps than to use two.

Disadvantages of an Integrated Amplifier

People who opt to buy an integrated amplifier must not readily compare its performance with a pair of separates. The fact is that the integrated performance may not be as dynamic because the power amplifier tends to degrade and interfere with the output of the preamp. Additionally, the power amp generates more heat than the preamplifier, which is not good for the electrical circuits. Another issue lies with part replacement and upgrading, where only one of the amplifiers needs to be upgraded or replaced, but the entire unit is affected.

Feature of Good Integrated Amplifier

Integrated amplifiers need to have carefully designed circuits with comprehensive cooling shielding. Buyers should compare their signal to noise ratio, frequency response, output power, and total harmonic distortion. Some amplifiers include pre-out and main-in ports, which allow separate accessibility to the preamp and power amplifier functions. This also allows bi-amping capabilities with an additional stereo power amplifier and bridged mono operation. Integrated amplifiers with the aforementioned features can be considered high-end, but other cheaper options may still have some of those features and perform well.

Channel Power

If buyers want to ensure that they get the best value and stereo sounds, they should select an integrated amplifier that has at least a 75 to 150 watts power per channel in 8 ohms. The specifications for most stereo integrated amplifiers are a RMS power output rate between 60 and 120 watts per channel. However, outboard power amplifiers generally have a higher output power rate of approximately 125 to 300 watts per channel.

The preamp circuit is close to the power amp in an integrated unit, and it can be difficult to prevent the power amp’s high voltage from causing interference with the preamplifier circuits, so they are generally made with lower watts per channel. However, some brands such as NAD, Marantz, and Technics have found a way to bypass that issue and create integrated amplifiers with higher watts per channel.

Amplifier Classes

Audio amplifiers are generally classified in alphabetical classes in accordance to the configurations of their circuit and their mode of operation. The names used to designate their classes are letters in alphabetical order, starting with Class A. However, classes may also intertwine based on their efficiency and signal reproduction, such as Class AB.

These various operation classes can range from an almost linear output with lower efficiency to a completely non-linear output with a higher efficiency. It is safe to say that no specific operation class can be considered better than another class when the mode of operation is being defined by using the amplifier circuit. There are various amplifier classes that are used today, but the most popular ones are listed below.

Class A and B

Class A amplifiers have a low efficiency, generally less than 40 percent, but they also have good linearity and signal reproduction. Class B amplifiers have double the efficiency of a class A amplifier and supreme theoretical efficiency of approximately 70 percent due to the fact that the power that the amplifying device conducts and uses is for only a fraction of the input signal.

Class AB and C

Class AB amplifiers have an efficiency rating that falls between the Class A and B amplifiers, but they also have a poorer signal reproduction when compared to the class A amplifiers. Class C amplifiers can be considered as the most efficient amplifier class because they only amplify a very small portion of the input signal, so the output signal does not greatly resemble the input signal. However, Class C amplifiers also have the worst signal reproduction.

Amplifier Classes Comparison Chart

The operation class for amplifiers can also be considered when buying a new one. The class is based on the transistor bias amount that the operation requires, along with the required input signal amplitude. In essence, the classification of an amplifier takes into consideration the amount of input signal that is conducted by the transistor. It also determines the efficiency and the amount of power that is consumed and dissipated as wasted heat by the switching transistor. The table below attempts to compare the most common amplifier classification types.






Conduction Angle

360 degrees

180 degrees

180 - 360 degrees

Less than 90 degrees

Q-point Position

Load line centre point

On the x-axis

Between the x-axis and the load line centre

Below the x-axis


25 to 30 percent

70 to 80 percent

50 to 70 percent

Over 80 percent

 Signal Distortion


Cross point of the x-axis and the load line

Small amount

Large amount

More powerful transistors may be required for Class A amplifiers with a less than perfect design. They may also need more expensive cooling fans and heat sinks, or maybe an increase in power supply size to provide the extra power that the amplifier needs. As a matter of fact, any electronic circuit that converts power from resistors or transistors into heat is ultimately going to be inefficient and almost always ends in premature failure.

Many buyers are probably wondering why a Class A amplifier would even be considered, but even with a lower efficiency rating, a Class A amplifier is often selected over a Class B. This may be due to the fact that Class A amplifiers provide a higher linear output, which means that it contains linearity over a higher frequency response, but it actually utilizes more direct current power.

How to Buy an Integrated Amplifier on eBay

Buying an integrated amplifier on eBay is very easy. All you need to do is type "integrated amplifier&" in the search field on the eBay home page to begin. This search will return results pages with multiple types of integrated amplifiers. You can then opt to manually browse through these results until you find an appropriate item, or you can enable various filters to narrow the list down to a number that is easier to navigate.

There are many filters that can be engaged, including amplifier type, brand, audio inputs and outputs, number of channels, RMS power, and condition. After the necessary filters have been enabled, you can then input a price range to find the right amplifier that fits into your budget.

If you are already sure of some of the features and specifications that you want on your integrated amplifier, you can modify your search to filter the initial search results. For instance, you could type "NAD integrated amplifier&" or "5 channel integrated amplifiers".. In sum, feel free to input any specific details from the beginning and then filter in the rest as you go along. When all searches are complete, contact sellers and confirm the specifications of the item as well as shipping details before you make your payment.


Buyers who opt for integrated amplifiers have to first understand the pros and cons of selecting that option. In essence, there should be no surprises when their amplifier is installed. Once their mind is set, they need to consider certain factors to suit their needs and taste. They should first think about what the use of the integrated amplifier as different amplifiers have different features, which can have different effects. A buyer’s budget is going to also play an integral part in the decision making process, so buyers may need to find an economical choice that efficiently meets their basic amplifier needs.

Buyers with a smaller budget have to decide which features are more important to them and select a model that has the most features if they cannot get them all. Class should also be taken into consideration but may not be a major factor in the decision process. Finding the right integrated amp is quite easy to do on eBay, because eBay’s powerful internal search engine and filter options simplifies the process.

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