i bought a new cd/mp3 radio.. after i correctly installed everything,,, i turn it on..

[the volume level is 0-60]

but when i put it between 1-20 its cool. but then higher than that i would loose all the sound and would be able to hear anything.

i bought the car used..

but before it was cool when i bought it. and it was also an after market cd player also. the thing is that one got jacked. so i had to replace it.

can someone PLEASE help me out why this is happening.

does the car come with a low wattage speaker that it cannot take the pounding. or is there a ground somewhere?