OK have played around a bit, turns out the Aego M sub woofer has an RCA output anyway it's just it goes from RCA to 1/8 jack.
Changed that for a decent quality RCA and I can confirm that there is a lot of difference!
I wouldn't say that the quality is that much better, but it is about 10 times as loud which is good for me.

As I'm less bothered about the sound quality and loudness from the outdoor speaker (can't see too many occasions when all the neighbours will be out!) I'll probably just run that through the headphone jack to my amp.

Thanks again everyone you've opened my eyes.