Fosi Audio P1 Tube Pre-Amplifier Mini Hi-Fi Stereo Buffer Preamp 6J1 Valve & Vacuum Pre-amp with Treble & Bass Tone Control for Home Theater System(with Power Supply) : Amazon.ca: Electronics
Ampeg Classic Analog Bass Preamp Pedal : Amazon.ca: Musical Instruments, Stage & Studio
Guyker 2-Band Preamp/Tone Control with Adjustable Gain for JB Bass (with Jazz Bass Control Plate, Dome Control Knobs and Stacked Knob) : Amazon.ca: Musical Instruments, Stage & Studio