But knowing what to look for makes all the difference between a great purchase and an expensive disappointment. Here is what we check before an amplifier goes on our shelves, and what we think you should be thinking about before you buy.
What type of amplifier do you actually need?
Before anything else, it is worth being clear about which type of amplifier fits your setup.
An integrated amplifier combines the preamplifier and power amplifier in a single box. It is the most common starting point for a stereo system and the right choice for most people. Brands like Naim, Cyrus, Cambridge Audio and Audiolab have all built iconic integrated amps over the years, and every one of those turns up on the pre-owned market regularly at compelling prices.
Pre-amplifier and power amplifier separates are exactly what they sound like: two boxes instead of one. The preamp handles source selection and volume control, while the power amp drives the speakers. Separates generally offer higher performance ceilings and are a natural upgrade path if you already own a good power amp or preamp. They suit listeners who want to mix and match, and they become genuinely exciting territory in the pre-owned market, where you can pick up genuinely high end components at accessible prices.
Streaming amplifiers have a built in network streamer, so you can play music from Spotify, Tidal, or your own library without a separate source component. If simplicity matters to you and you want a single box that does everything, this category is worth exploring.
Headphone amplifiers are dedicated units designed to drive headphones properly, as most amplifiers do not have the right output impedance for the task. If headphone listening is important to you, a dedicated headphone amp makes a real difference.
Getting this choice right first narrows the field considerably.
Power output: how much do you need?
Wattage matters, but it matters less than most people assume and in a different way than most buyers expect.
A 50 watt integrated amplifier like the Cyrus One or Audiolab 6000A is more than enough to fill a typical living room with a reasonably sensitive pair of speakers. On the other hand, a demanding loudspeaker like those from ATC, which are designed to be driven by serious amplification, may need a 100 watt power amplifier or more to perform properly.
The key variable is your speakers. If you know their sensitivity rating (measured in dB), that tells you a lot about how much power they actually need. Low sensitivity speakers (below 86dB) will ask more of an amplifier. Higher sensitivity designs (above 90dB) can sound spectacular from a modest 30 to 40 watts.
When buying pre-owned, check the rated power output of any amplifier you are considering and match it to your speakers. We are always happy to advise if you are not sure.
Solid state or valves?
This is the question that generates more discussion in hi-fi than almost anything else, and there is no single right answer.
Solid state amplifiers (sometimes called transistor amps) use modern semiconductor circuits. They tend to be more consistent, require less maintenance, and are generally more reliable over the long term. Naim, Cyrus, Musical Fidelity, Chord Electronics, Arcam and Cambridge Audio all build solid-state designs, and these make up the majority of the pre-owned market.
Valve amplifiers (sometimes called tube amps) use glass vacuum tubes in the signal path. They have a particular sonic character that many listeners find natural and involving. Brands like AMC and Unison Research offer valve and hybrid designs that are well regarded for their warmth and musicality. Valve amps do require periodic tube replacement, which is a running cost to factor in, and they generally run warmer and use more power than their solid state equivalents.
Neither is inherently better. The question is which one suits your preferences, your speakers and your lifestyle. If you have never heard a valve amplifier, it is well worth listening before you decide. If you want something you can leave running all evening without thinking about it, solid state is usually the more practical choice.
What to check physically
When we receive an amplifier, this is what we look at carefully before it goes anywhere near a listing.
The front panel should be clean and the controls should move smoothly. Volume pots and source selectors can develop a crackle or a scratchy feel when they have not been used for a while. A light clean or a spray of contact cleaner usually sorts this, but it is worth knowing about before you buy.
Speaker terminals should be firm and clean. Loose or corroded terminals cause problems with the connection to your speakers and are harder to resolve than they look.
The rear panel should have all its sockets present and intact. Check that no RCA inputs are bent or damaged, and that any speaker binding posts are in good condition.
Look at the overall cosmetic condition honestly. A few small marks on the top of a casework are normal on a piece of equipment that has been in regular use. Deep scratches on the fascia or significant dents suggest the item has not been cared for well, which may reflect on how it has been used generally.
We photograph every amplifier we sell in detail, including any marks, so that you can assess the condition for yourself before you commit.
The inputs question
It sounds obvious but it is easy to overlook. Count how many inputs you need. If you have a turntable, a CD player, a streamer and a TV, you need at least four inputs. Many older integrated amplifiers were designed in an era when most systems had three or four sources, so they have plenty. Some modern minimalist designs have fewer.
If you have a turntable with a magnetic (MM or MC) cartridge, you will also need a phono stage. Some integrated amplifiers have one built in. Others do not, in which case you will need a separate phono stage between the turntable and the amp. Worth checking before you buy rather than after.
The brand question
This is where experience really helps, and it is one of the reasons buying from a specialist dealer makes sense.
Certain brands have a well earned reputation for long-term reliability. Naim amplifiers, for example, are known for their longevity and are often serviced and upgraded by their owners over many years. Cyrus and Musical Fidelity have similarly strong reputations. Cambridge Audio and Audiolab tend to be straightforward and reliable in everyday use.
At the higher end, brands like McIntosh from the United States or T+A from Germany build amplifiers that are genuinely engineered to last decades and hold their value well. These turn up in the pre-owned market less often, but when they do they represent serious value.
More exotic brands like Audio Research or Aesthetix occupy the serious high end territory. Their amplifiers are built to a very high standard but may be more costly to service if something does need attention.
None of this means you should avoid lesser known brands entirely. AMC, for example, has been building solid amplifiers for a long time and represents excellent value. But if you are buying from a private seller rather than a dealer, brand reputation and parts availability become more important.
Why buying from a dealer matters
When you buy a used amplifier from a private seller, you are taking their word for everything. It was working when they boxed it up. There are no issues they know of. Good luck.
When you buy from us, you get something different. Every amplifier is tested before it is listed. We describe the condition accurately and photograph it honestly, including any marks or wear. And every item over £100 comes with a six month warranty covering parts and labour.
That warranty is not a formality. Amplifiers can develop faults over time, even well made ones, and a six month window gives you genuine peace of mind that if something does go wrong, it is our problem to fix.
We also know the stock we carry. If you are unsure whether a particular amplifier will work with your speakers or your source equipment, get in touch and ask. We are a specialist hi-fi dealer and we are happy to talk through your setup before you spend any money.
Browse our current amplifier stock at 2ndhandhifi.co.uk/collections/amplifiers.