F430 audio only from 1 speaker

Hello and welcome.

Do the rest of the inputs sound proper? CD/Radio?

If they're also bad, there's a chance you have a bad amp which is not uncommon. The audio guru here is Mike from Scuderia Audio (@SoftwareDrone).

 

Thanks Joe.
I hear this story almost weekly. You most likely have either a transistor (there are four) or a capacitor blown in your booster (located under the dash).
You have several options. You could purchase a new, replacement booster. They cost around $1,600.00. The good news is that you'd have a brand-new booster, but the bad news is that the Ferrari boosters have only 60 Watts of power and an incredible 10% distortion (the human ear can detect distortion levels at anything above 0.2%). You could have your booster refurbished for a few hundred dollars. But in the end, you'd still have a Ferrari booster with its dismal performance. Or, you can get a Super Amp from Scuderia Audio. It's a 420 Watt, plug and play, direct swap out unit with a lifetime guarantee. It will sound like you have a completely new sound system as it produces much more power to all the speakers in the car. I've sold almost 500 of these worldwide, and there are plenty of people here who will attest to the quality. PM me with any questions.
https://scuderiaaudio.com/product/360-430-super-amplifier/

 

Best first upgrade of the sound system I did.