Kac-8104d kenwood channel amplifier.
Product highlights:

monkey subwoofer amplifier

300 watts RMS x 1 at 4 ohms (500 watts x 1 at 2 ohms)

CEA-2006 compliant

variable low-pass filter (50-200 Hz at 24 dB per octave)

bass boost (0-18 dB at 40 Hz )

subsonic filter (15/25 Hz, 18 dB/octave )

Class D design

speaker-level inputs with signal sensing turn-on

preamp-level inputs and outputs

fuse rating: 40A x 1

8-gauge power and ground leads recommended — wiring and hardware not included with amplifier