PHP Sound Shocker Pro Review - Boost Your 3.5'' Aux Volume
Sound Shocker is a passive audio preamplifier that boosts any headphone
output by about +20dB and provides a proper line level output impedance.
This means that the headphone output of your player, phone, laptop, etc. will
sound about 4 times louder for the same volume setting when connected to
the AUX input of your stereo. All this with NO Batteries, NO Switches, just
Plug-and-Play.
http://www.phpaudio.jigsy.com/passive...