Competition / Reference Grade ($$$$ )

• Sundown Audio (USA) — Z, X, SA series (SPL competition)
• DC Audio (USA) — Level series (extreme SPL)
• Fi Audio (USA) — BTL, Q, SSD (custom builds)
• Crescendo Audio (USA) — Forte (high-power SPL)
• American Bass (USA) — Competition woofers
• Skar Audio (USA) — VVX, EVL (value SPL)