REL S/550: Speed, Output and Musical Integration
The REL S/550 sits in REL's S series, the range where the company pursues greater output and greater speed than its entry tiers while holding onto the musical integration that defines the brand. It is a sub-bass system in REL's language, engineered to disappear beneath your main speakers and give you the foundation, air and scale that full range music and film both depend on.
What makes the S/550 distinct is its hybrid enclosure. A 10 inch forward-firing long-throw alloy cone acts as the active driver, energized by a 500 watt Class D amplifier, while a 12 inch down-firing passive radiator loads the room and helps the sealed cabinet reach down to roughly 21 Hz (-6dB in room). The result is a sub that pressurizes a room with authority yet starts and stops with the agility a closed box design is known for. This is bass that follows the leading edge of a kick drum or a cello line rather than lagging behind it.
The High Level Connection and Why It Matters for Music
REL's signature is the High Level connection, and the S/550 offers it through a Neutrik Speakon input. Instead of pulling a line level signal from a preamp, you take a light gauge cable from your power amplifier's speaker terminals directly to the sub. The S/550 then receives the very same amplified signal your main speakers see, complete with the tonal character and voicing of your amplifier. This is the heart of REL integration and the reason RELs blend so naturally into two-channel systems. The sub does not sound like a separate device bolted on; it sounds like an extension of your existing speakers.
For film and multichannel, the S/550 also provides a dedicated .1/LFE input alongside a low level RCA input. Run the LFE feed from your processor or receiver and let its bass management handle the low frequency effects channel, delivering the slam and rumble a soundtrack calls for. Many owners wire both the High Level and the LFE connections at once, using High Level for the seamless musical layer and LFE for movies, then simply choosing the source at the front of the system.
Controls That Make Setup Straightforward
The S/550 gives you a continuously variable crossover, a level (gain) control and a phase switch. The variable crossover lets you dial the handoff point to match how deep your main speakers already play, the level control balances the sub to the room, and phase lets you time-align the sub with your mains so the two arrive together at your listening seat. These are the tools that turn a good subwoofer into an invisible one.
Matching the S/550 to Speakers and Rooms
The S/550 is well suited to medium and larger rooms and to floorstanding or stand-mounted speakers that want reinforcement below their natural roll off. If you are building around a refined stand-mounted system, speakers on a set of Gauder Akustik Capello 40 Aluminum Stands pair beautifully with an S/550 filling in the bottom two octaves. On the amplification side, the High Level connection works elegantly from an integrated amplifier such as the Audiolab 9000A, which gives the S/550 a full, characterful signal to follow.
Because it reaches to around 21 Hz in room, a single S/550 covers most two-channel and film needs. Larger rooms or listeners who want a bigger soundstage can run two in a stereo pair or a stacked line array for greater output and even more effortless dynamics. Placement typically starts in a corner near the main speakers, then you fine tune by ear using the level, crossover and phase controls.
Completing the Hookup: Cables and Wireless
For the High Level run, REL's Bassline Blue style cabling is the traditional route, and a dedicated bass speaker cable such as the AudioQuest BigFoot BASS is a refined choice for feeding the Speakon input, with full-range speaker cable like the AudioQuest Lone Ranger serving your mains. For the LFE side, the REL Commander is purpose built for the .1 connection, and AudioQuest offers a family of subwoofer cables to suit, from the Boxer and Greyhound to the Irish Red and the balanced Husky in XLR or RCA.
If a wired run across the room is not practical, the S/550 is compatible with the optional REL AirShip II wireless system, which transmits the signal to the sub without a physical cable. REL also offers other wireless solutions such as the HT-Air MKII and Arrow for their respective compatible subs. A wireless transmitter makes no sound on its own; it serves a specific compatible subwoofer, so confirm the S/550 and AirShip II pairing before you buy.
Where the S/550 Sits in the REL Range
Within the S series, the S/550 is the natural starting point for listeners who want serious speed and output in a compact, beautifully finished cabinet available in high gloss black or high gloss white. If you have a larger room, more demanding main speakers, or you simply want more headroom and lower extension, the REL S/850 steps up the S ladder with a larger driver system and greater output for the same integration philosophy. Both share the S series DNA; the choice comes down to room size, main speaker scale and how much reserve you want on tap.
Ideal System and Use Case
The S/550 is at its best in a music-first system that also does duty for film. Its closed box and passive radiator design gives you tight, tuneful bass for two-channel listening through the High Level connection, while the dedicated LFE input handles home theater slam when the lights go down. If your priority is pure dedicated theater in a very large space, REL's HT series is optimized specifically for LFE output, but for the listener who wants one sub that sings with music and delivers on movies, the S/550 is a compelling all-rounder.
Frequently Asked Questions
What cables and connections does the REL S/550 need?
For the High Level run, REL's Bassline Blue style cabling is the traditional route, and a dedicated bass speaker cable such as the AudioQuest BigFoot BASS is a refined choice for feeding the Speakon input, with full-range speaker cable like the AudioQuest Lone Ranger serving your mains.
Where does the REL S/550 sit in the range?
Within the S series, the S/550 is the natural starting point for listeners who want serious speed and output in a compact, beautifully finished cabinet available in high gloss black or high gloss white. If you have a larger room, more demanding main speakers, or you simply want more headroom and lower extension, the REL S/850 steps up the S ladder with a larger driver system and greater output for the same integration philosophy.
Who is the REL S/550 best suited to?
The S/550 is at its best in a music-first system that also does duty for film. Its closed box and passive radiator design gives you tight, tuneful bass for two-channel listening through the High Level connection, while the dedicated LFE input handles home theater slam when the lights go down.
Come Listen
AEA is an authorized REL Acoustics dealer with a showroom in Timonium, Maryland. Demo units rotate and not every model is always set up, so please reach out to arrange a listen or to let us help match the S/550 to your speakers, amplifier and room.