SMC-1 - Stereo/Mono-Konverter 1 x Stereo auf 2 x Mono | UMZ | Musikus Hifi Shop
Monacor | AV-Connection
MONACOR FGA-30 Mass filter 3.5mm jack
User manual Monacor SMC-1 (English - 2 pages)
Audio Equipment: Is there a method/device to connect a subwoofer LFE output from a stereo to a subwoofer that only has a pair of speaker-level inputs? - Quora
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Amazon.com: OSD Audio SMC21 Stereo to Mono Converter – Gold-Plated RCA Connections and 1:1 Ratio Audio Transformer : Electronics