Low volume Aux input

I have an iSimple unit that works fine with my ipod but when I try to use the 3.5mm for my Android phone the volume level is almost half what it should be compared to AM/FM/CD.

I've tried just tapping into the wires as this thread suggests:
http://acurazine.com/forums/audio-bl...io-aux-577329/

But it has nearly the same low level issue as the 3.5mm jack in the iSimple.

Further research led me to a possible line driver solution:


Any advice?

Thanks!