Auxiliary Input: Front Auxiliary Input (Mini-jack) is often included on similar models like the DPX-MP4100, which is useful for connecting modern devices like smartphones/MP3 players. Pre-outs: Two sets of Preamp Outputs (RCA), typically 2.5V, allowing connection to external amplifiers for better sound quality and power (e.g., one set for front speakers/full range, and one set switchable for rear speakers or a subwoofer).
eBay