Speaker load box form Palmer in good used condition
From the manufacture:
Special DI box with loadbox for guitars. The integrated load resistor permits tube amplifiers up to approximately 120 W to be connected to the PGA04, bypassing a loudspeaker. A jack socket (unbalanced) and balanced XLR connector are available for direct pickup of the signal. The extensive filter section provides for a realistic simulation of classic guitar loudspeaker sounds.