There are one HotPlate model for each impedance. A 2015 Marshall JMP 1987X set at 8Ohm with a 1970 Marshall 2x12 of 8 Ohm. Is played with both a 8 Ohm and a 16 Ohm (mismatch) attenuator. Guitar: 2008 Gibson Les Paul Standard 1959 Reissue R9. Hoplates set a -16dB with the continous knob at 9:00.