You mean if voltage on ADC is over +5V?
That was what i was concerned about too, but i cant measure 3.5mm uotput when music is playing, because it is too fast for my multimeter. But i think the voltage i can get is very low even when loud music is playing, isnt it?
And i know about softever problem, but i have LM3915 on my first vu meter and it is not interesting. I want to have an options. And i hope i would be able to make it work with atmega. I like one mode that i have seen: its like regular vu meter bar mode, but with upper led going down very slow. Thats what i want to do
Here is my inspiration: