It's the heart of your hi-fi system; the engine that drives your music from source to speakers, and amplifies the signal so it sounds loud and proud.
But with laptops, smartphones and streaming services gaining ground as music sources, the stereo amp has had to evolve, with built-in DACs (digital-to-analogue converters), USB connections and wireless streaming capability now becoming increasingly important.
Don't become obsessed by power figures when buying an amplifier – more power doesn't necessarily mean better sound. A relatively low-powered amp can still sound sweet with the right speakers. And unless you intend to play your system at party levels all the time, it's important to pay just as much attention to attributes such as timing, dynamics, precision and control.
This £300 Marantz sets the bar even higher than its illustrious PM6004 predecessor, and it's equipped for the digital age too.
For a budget amp, the PM6005 comes in a sturdy metal chassis, sounds spacious and organised, delivers music that's full of energy and detail and now sports a smattering of digital connections.
An optical input lets you make use of the DAC (though we wouldn't mind a USB connection), and the Marantz supports high-res audio, too. Of course you also have all the standard analogue audio inputs.
Most crucial is the top-notch sound quality, this hi-fi amp proving capable no matter what system you build around it. It's no surprise it was our 2014 award-winner.
You might expect a big, room-filling sound from an amplifier at this price but the Arcam A19 certainly doesn't disappoint.
Solid build - FMJ stands for 'Full Metal Jacket' - is matched by a thorough specification and subtle but expansive sound.
You need to be a little careful with system matching - see the full review for details - but get it right and this is a hugely-capable stereo amplifier.
An excellent amp for the money, and a fine addition to any hi-fi system, this Rega accomplised the unenviable task of shaking-up a market dominated by the likes of Cyrus, Naim and Roksan.
A good phono stage is a bonus for anyone looking to connect a turntable and a slightly underwhelming remote is about our only issue with this music amplifier.
Talking of the Elicit-R (see above), it's our favourite model as we move up the price spectrum.
A five-star amp from the get-go, this Rega benefitted from some price changes to rival products to leave it out on its own as one of the best amps on the market over £1000.
Full of revealing detail and superb rhythms, this is a truly fantastic amplifier. Great build and finish complete the package.
There are always new rivals around the corner, such as the Roksan K3, but for now the Rega remains our pick.