Check the listing for details. Boss GM-800 Guitar Synthesizer Pedal. Condition: New. Listed at 846.99 USD. Next-gen Guitar Synth with Flagship-quality Sounds The BOSS GM-800 is a next-gen guitar synthesizer pedal driven by Roland's Serial GK interface along with an advanced Zen-Core sound engine culled from Roland's flagship synths. The pedal's high-performance DSP elicits a natural playing feel and solid tracking, while its vast onboard sound library gives you plenty of room for inspired creativity. Employ the GM-800's intuitive Scene workflow to freely combine and modify Tones, add color to sounds with a wide range of effects, and discover a world of brand-new content on Roland Cloud. You also get two external control jacks, USB audio/MIDI and standard MIDI connectivity, and a Serial GK expansion jack for connecting to other BOSS guitar synthesizer units.