I have a receiver with impedance range 8-16 ohms, which came with 3 speakers.
I have 2 speakers from an old stereo I would also like to drive with this receiver.
However, the 2 speakers have an impedance of 6 ohms so they are very quiet in comparison to the other 3 speakers.
A little research has indicated that there are devices that perform impedance matching. However, I have not yet been able to find one.
I am not sure if I need a device to match the impedance of the receiver or a device to amplify the receiver signal for the 2 speakers.