What are wrong with my speakers?

[Jimmy Bro]

So lately, when watching Blu-rays on my PS3 (which is connected to a 10 or so year old Yamaha receiver and Klipsh speakers) the sound has gotten kinda bad.

A few months ago, having the volume on around -20.0db or -19.0db was a comfortable volume and sounded clear and good. But recently, those volumes just don't seem loud enough any more, and I'm having to go down to like -14.0db to make up for it, but the quality just doesn't sound as clear at that level, and every now and then it will make a little crackle and the left speaker will become like twice as loud as the right speaker.

It's getting really annoying and it's making it harder to enjoy watching stuff. Anyone had a similar experience to this or know what the hell might be causing this? I'm not even sure if it's a speaker problem, perhaps it's the receiver or the PS3? But I had a look at the settings for both and nothing seems to be out of order.

For 10+ years this system has sounded nice and clear and now it's crap. Why?