Monoprice 611720 20-Watt 1x8 Guitar Combo Amplifier - Black With 86dB of Gain, 1/4 Inch, Headphone and 3.5mm Aux Mp3 Inputs For Electric Guitars Crank it up to 11 using this 20-watt, 1x8 Guitar Combo Amplifier from Monoprice! 8-inch, 4-ohm speaker. Overdrive tone with 86dB of gain It has a line level output, which allows you to send the output to a recorder or mixing board. It also features a 3.5mm AUX IN jack, which allows you to plug in an mp3 player so you can play along to your favorite tunes.