With iTunes, Ring tones, Mp3, M4a, M4r, AAC, WMA, Wave files and since I've just about covered them all, my question is as follows:

With iTunes software to download and or rip music can come from various sources as mentioned above. The volume from one song to another depending on the source differs sometimes drastically. When listening to music from my Iphone8G through my FM transmitter in my X5, I find it annoying to have to continuously ride the volume control. What is my best method of normalizing, converting, and or sound checking this apparent problem. Iíve read and read hundreds of threads and I do not believe anyone has covered this issue. Iíve even contacted several individuals with iPods and they have the same problem. Is there a fix or an area in iTunes that supports this concern?