It might be slightly less bad but the ratio between maximum excursions is only 1.6, giving you 4dB more (potential) volume - barely perceptible.
You'd be better off either moving to a larger radiating area - a bigger driver (a 4 inch woofer is an oxymoron!) - look for one whose output doesn't roll off before the bottom of the band of interest.
Or if you can't afford the space, perhaps a tuned port to augment the output around 100Hz. Port tuning can be tricky, but there are loudspeaker enclosure design programs that will help. You're probably looking at an esclosure volume of about 4 litres with a fairly small diameter (25 or 30mm) port as a starting point.
Alternatively : is the speaker being driven outside its linear range by frequencies below the band of interest? Perhaps a high pass filter set to 80Hz will pass all frequencies of interest but protect the speaker from high amplitude 20-50Hz signals that can only drive the cone out of its linear range and potentially cause damage.
Yes, it is allowed to have that variable a load on your amplifiers, given certain precautions. Most amplifiers can tolerate open circuit on their outputs, and, subject to limiting the output so they don't get too hot, somewhat lower than their 'rated' load.
A common method for supplying multiple speakers from a central location is the '100v line' method. Each speaker has a transformer before it to raise its impedance. This can get expensive in transformers, that have to be rated for the audio range.
You should be able to buy high impedance speakers, 32 ohm is not uncommon. Ten of those in parallel would present around 3ohms to your amplifier, which most audio amps should be able to drive at less than max output with little distress. How much fi and power do you want, I suspect these higher impedance speakers will be lo-fi and low power.
You could precede each speaker by its own local amplifier, which would raise the per room loading to a level where it ceases to be an issue. If powering the amplifiers via the CAT5, you would want a beefy electrolytic across the supply at the amplifier.
Best Answer
Beneath that big black control knob is a potentiometer. Over time, the contact surface of that potentiometer has deteriorated, to the point where the potentiometer's slider no longer makes consistent contact with the surface all the way around.
You need to remove the knob, de-solder the potentiometer, and replace it with one of the same resistance range, same "law", and same dimensions.