Amazonhas theBrainwavz AP001 Portable Headphone Amplifier for a low$16.50 after Coupon Code: "9EDKUG6N" (Exp Soon). Free Shipping on orders $35+ or with Amazon Prime membership. Tax in many states. This is around $27 elsewhere, so you are saving about 38% by taking advantage of this deal. Headphone amps aredesigned to help deliver more power to your headphones or portable speakers than your standard iPod, iPhone, smartphone or MP3 player. 4/5 rating on Amazon with over 100 reviews OP AMP for powerful and clean volume, with bass enhancer Stereo line in and dual stereo line out (two people can listen) Auto power on and off, depending on whether audio is coming thru or not Supports 16 ohm-150 ohm earphone & headphones Built in 120mAh rechargeable battery, provides 12 hours of continuous usage