Manual Bias Kit - Miller Audio Black Dyna-70 Ultimate Upgrade Amp w/ Alum Face Plate $1,950.00 Nickel Dyna-70 Ultimate Upgrade Amp $2,100.00 Brown Dyna-70 Ultimate Upgrade Amp with Tube Cage $1,950.00 Copper Dyna-70 Ultimate Upgrade Amp $2,100.00 Dyna-70 Ultimate Upgrade Manual Bias PCB $60.00 Dyna-70 Ultimate Upgrade Kit, Manual Bias $349.95