What the Resolut SRC remote does, which Resolut processors it works with, the cheaper potentiometer alternative from Resolut's manuals, and who actually needs one.

Hertz's compact Dieci Power mono amplifier makes 500 W RMS at 2 ohms and works with factory head units. Specs, what the 1180 W figure means, the HRC 02 remote and the right subwoofer.

The Alpine HDA-M80 is the Status range's mono subwoofer amplifier. Its power at 4 and 2 ohms, which subs suit it, its filters, the optional RUX-KNOB.2 bass knob, what owners say, and how it compares with Alpine's cheaper and more powerful monos.

The Alpine HDP-D90 is the Status range's DSP amplifier: 12 amplified channels, 10 pre-outs and deep tuning. Its inputs, power, tuning, when you need the RUX-C810 controller, how it compares with Alpine's PXE-X processors, and the fact that we found no owner reviews.

The JL Audio HD RBC-1 is the catalogue's bass remote for HD and XDM amplifiers. We explain its link to JL's HD-RLC, which amplifiers it suits and what to confirm before buying.

The JL Audio RBC-1 puts subwoofer level on a knob by the driver's seat. Here is which JL amplifiers it is listed for, when it is worth adding, and what it costs.

Which JL Audio products the DRC-205 wired remote works with, when you actually need one, how it compares with the VXi-BTC, and what it costs in India.

What Zapco's HB DSP II-R remote controls, which HB II processors it works with (and which it doesn't), and whether it's worth adding instead of relying on the phone app.