REL makes superb active subwoofers in general and this one is so good, it is peer to at least one 15in model and other products nearly twice the price. In the S5, driver and amplifier engineering have created a new benchmark.

This £1,600 sub uses a massively solid box with a chunky ‘feature’ grille that is easy to remove, and four thick supports to hold it off the floor. Bars on the side help you lug it about – it weighs 31kg – and design ticks include a logo badge on the top plate in a metallic finish. A wireless model in glossy black or white only (I'd like a wood option), it has a small aerial socket and a flip switch on the back. When used with REL’s Longbow transmitter (an optional extra), it will pair and receive the bass signal as a composite of both high-level from the speaker feed and the low-level phono input. The S5 has direct-connection sockets on the back too, adjusted by crossover knob but separate gain controls for both high- and low-level inputs. You also get a 10m cable with a Speakon plug.

The 12in long-excursion front driver has a large surround and 550W of Class D amp to drive it. Underneath, floor-firing, is a thin 12in disc of high-tech carbon fibre, also on a roll suspension. This is passive and offers the S5 benefits over ported or sealed designs.

Now the time is here

Iron Man 3 on Blu-ray had its plastic wrapper broached, and screened for the first time since I saw it at the flicks. I connected the S5 via a Y lead to both my amp's phono stereo sockets, as well as using the Speakon plug fixed to the main outputs. It was very easy to setup and get a good result, yet you will no doubt tweak the gain levels for a movie or three initially.

The first and best thing immediately apparent of the S5 is the scale it gives to the whole multichannel soundfield. It will make all your speakers sound effortlessly larger and more dynamic, not just add low-end boom.

Of course, the spectacular effects you would want for this sort of spend do not disappoint. As it is sealed, it is tight and fast. And as it has a passive bass radiator, it can be explosive and drop like a stone to play real infrasonics. At the line, 'Do we need to worry about that?' Stark’s house gets blown up. If you can hear/feel the heartbeat at the very end of this mayhem-filled sequence, then you may well have a REL. 

This woofer can be seen to reach a limit but if you find it your home will likely be shaking with structure-borne bass as you do so. And, yes, it's hardly cheap, but I'd argue it offers fantastic value; as good as REL's previous Stentor but for a good chunk less. And if you need more, REL's Gibraltar range is for certifiable types, or castle owners. A definite audition for serious cinema-hedz with sizeable budgets.

REL S5, £1,600, www.rel.net

Verdict: 5/5