S/510

The S/510 is REL's flagship S-series engineering at 10-inch scale — a 10-inch front-firing active driver paired with a 10-inch downward-firing passive radiator, driven by a 500W Class A/B amplifier. That hybrid design is fundamentally different to the single-driver-plus-power approach the SVS line takes, and the audible result is a different kind of bass.

This is musical bass, not impact bass. The S/510 fills out the bottom octaves of a high-end stereo system in a way that completes the music rather than adding to it. Class A/B amplification gives a different harmonic character than the SVS Class D — softer at the leading edge of transients, more present in the body of sustained low notes. Combined with the Neutrik Speakon high-level connection (same philosophy as the T/7x further down the line), the sub takes its signal from the amp's speaker terminals and stays coherent with the mains in a way line-level designs can't.

For cinema-leaning rooms where LFE punch matters more than musical integration, this is the wrong sub. The SB-4000 at similar money will deliver more raw SPL, more demanding-scene headroom, and tighter time-alignment for film effects. The S/510 is engineered for the system that already sounds excellent in stereo and needs the bottom octaves filled in coherently — not for the system that needs LFE impact.

The audiophile-flagship sub — right for stereo systems that already sound excellent, wrong for cinema-LFE rooms.