What is your opinion about solving the problem of connecting a 4-ohm impedance speaker to an amplifier that only drives 8-ohm speakers by adding a 4-ohm resistor connected in series with the speakers?
Resistor: 4 Ohm 100W
Amplifier: 140W per channel at 8 Ohm
The UB51 is a nominally 4ohm speaker. The impedance changes based on frequency. A 4 ohm nominal speaker means that it has areas of frequency that dips below 4 ohms. The Uni-Fi only dips in a very small frequency range, in the bass frequencies.