A and B parallel speaker outputs supports (4) 8 ohm speakers or (2) 8 ohm speakers or (2) 4 ohm speakers (Terminals are banana or bare wire). Built in Bluetooth with 35 Foot range. USB input will play music files from a thumb drive or hard drive (32gb max). SD card playback will play music files stored on a memory card (32gb max). Mic line input mixer: volume, balance, echo, and 3 band EQ. Music input mixer: volume, balance, and 3 band EQ. Full controls over echo effects: volume, 2 band echo EQ, repeat, and delay parameters. Selectable mono/stereo echo effect. Dual 7 band master EQ (left/right). Master mic volume control. Remote control for USB/SD playback and Bluetooth Full function. Built in quiet cooling fan. Perfect for karaoke, DJ, KJ, home, and commercial applications. Precision tuning with high quality professional potentiometers and knobs. 115V/230V switchable for worldwide use. Unit weight: 14 lbs (6.35). Unit dimensions: 13″ x 5″ x 1. Rockville SingMix 45 1000w Powered Karaoke Mixer Amplifier w/Bluetooth/USB/Echo. The SingMix 45 is a powered mixer that is suited for karaoke as well as PA applications. The built in stereo amplifier is extremely powerful and can easily support 2 speakers that are either 4 ohm or 8 ohm. You can even use this powered mixer for 4 speakers that are 8 ohm. What makes the SingMix 45 really unique is that it has 4 mic/line inputs that have individual EQ controls in addition to the master EQ. It also has a very advanced echo effect that includes echo volume, a 2 band echo EQ, as well as repeat and delay parameters. In addition to the 4 inputs you also can play back tracks through Bluetooth, USB, or SD. 4 Mic/line inputs – (2) ¼ Front and (2) XLR Rear. Front: USB/SD Inputs, built-in Bluetooth. (2) pair RCA Inputs (rear). (2) pairs RCA Outputs (1 master line out and one rec out). Speaker outputs supports 4 speaker or 2 speaker setups (banana or bare wire). Front 3.5 MM aux input. THD: less than 0.5%. Frequency response: (20Hz-20KHz): ±2dB. Signal to noise ratio: >78db. Tone characteristic (80Hz-15KHz) ±12dB.