Speco Speaker Volume Controller RMS 80W

Speco IMP80D impedance matching volume control.
The IMP80D is a unique adjustable designed impedance matching stereo volume control.
The impedance matching 2x, 4x, 8x or 16x switch positions enable the IMP80D to connect up to 16 pairs of 8 ohm speakers or 8 pairs of 4-ohm speakers to a single 8 ohm stable amplifier and operate them simultaneously without the fear of amplifier overload, eliminating the need for a speaker selector or other impedance matching device. (Note: When using a 4-ohm stable amplifier, you can connect up to 32 pairs of 8 ohm speakers or up to 16 pairs of 4 ohm speakers.)