The GLC 63S is a car that does everything well — and the audio should be no different. Due to worldwide chip shortages, even the 63S came with a completely standard sound system. It didn’t even have tweeters! This build covered the full system, front to back, with a strict brief: nothing visible.

Helix Ci3 speakers with FlexMount and WireKits went in at every speaker location — front doors, rear doors, and dash. FlexMount is Helix's flush-fit mounting system, designed specifically so the grille sits flat against the panel with no visible adapter ring or bezel. Combined with the OEM-matched WireKits, the install is genuinely invisible.

Footwell bass came from Match plug and play subwoofers — they slot under the front footwell using the factory mounting points, no fabrication required. The Match UP 6DSP handled amplification and signal processing for the main stage, connected via a purpose-built Mercedes harness. A separate Helix Amplify 201 Direct DSP amplifier ran a hidden Focal PSB200 subwoofer in the boot — tuned and time-aligned independently through the DSP.

The result is a full active system in a car where you'd never know anything had been done. That's the point.

Equipment:

• Helix Ci3 with FlexMount and WireKits — full front and rear stage

• Match plug & play footwell subwoofers

• Match UP 6DSP — main amplifier and processor

• Helix Amplify 201 Direct DSP — dedicated subwoofer amplifier

• Focal PSB200 subwoofer hidden under the false floor in the boot