Anyone can recommend cheap dsp? Plan to utilize the optical out from android car headunit. Saw some china one around 700-1000+.

My speaker is morel maximus ultra 602. Amp is sony xm-gs4. Got 1 dls subwoofer also at the back. Feel after install this android HU, the sound is really lousy compare my clarion cz702a but have to retire it because the unit got problem