Changed circ.breaker-vocals became shouty:why?

The vocalists are trying to warn you that your house may burn down! You can't just insert a 30 amp breaker in place of a 15 amp one. The rating of the breaker depends on the wire that it feeds into. A 30 amp breaker has the same resistance as a 15 amp one and, unless you believe in magic, has no effect on the audio signal. Either breaker will deliver the current that your audio system demands, and you can't make the audio system demand more by changing the breaker.

The 30 amp breaker would permit you to plug in a TV and an Airconditioner as well as your audio system, and a few other things, without the breaker opening. The wires will get hot, and even if you don't start a fire right away the insulation of the wires will be damaged, which is a long-term hazard.

What is the size of the wire between your outlet and breaker?

Ignoring your question, but you can't just up the amperage of the breaker unless you've upgraded all of the downstream wiring in the walls to match. Big fire hazard if you don't.

No idea why the sound would change.

Thanks for your replies.
The wire is 12 gauge.I will step down to 20 amp breaker.
The dynamics changed a lot with a 30 amp,a lot of headroom and the lights on my Panamax power conditioner are not flickering on the border of underpowering anymore.But fire hazard is something i don't want to play with.Once again,thanks to your advices.

Hello Again. You said nothing about the Panamax in line before. Take that piece of ?&$# out of the system. I am a Panamax dealer and that thing doesn't belong on anything above a $400 theater in a box. That is cutting the sound quality of your amp down about 30%. You need to be in a line canditioner above $2500 on that amp OR nothing at all. (my favorite is Shinyata. (don't know how to spell it because I am not a dealer. LOL)