The CA-2A DOES support side chain... Feature Highlights:• Meticulously modeled.
• Easy to use with simple controls.
• Warm, smooth and natural sounding compression.
• Frequency-dependent gain reduction.
• Compressor and Limiter modes.• Up to 40 dB of smooth gain reduction.
• Sidechain input for ducking, De-essing and pumping.• Gain reduction CV output to modulate other effects.
• Zero latency for real-time tracking and mixing.
• Fully modeled "R37" HF Pre-emphasis control.
• VST, Audio Units & ProChannel compatible.
Just an FYI...whether the side chain works in Limiter mode I can't say, as I've never used
it that way..