Does your mp3 need extra grunt then I suggest this I have bought 2 so far and really impressed with them .. since my NWZ-A845 is EU sound restricted this makes all the difference.. Also works really well with my LC Turtle Beach Headset.
E5-portable headphone amplifier World’s smallest metal case headphone amplifier The E5 is a Portable Headphone Amplifier designed to improve the sound quality and volume of any Digital Audio Player such as a MP3 or MP4 Player Mobile Phone Laptop or Notebook. Following up on the ever popular E3 headphone amplifier the E5 creates a whole new listening experience. While the E5 retains all the advantages of the E3 it has gives your listening experience a kick with some great new features of its own! It is encased in a tiny metal unit so small it's barely noticeable - only 44.2mm x 38 mm x 12.6 mm! The E5 has an excellent in built volume control so now you can connect directly to the line out of your digital audio device and control the volume directly from your E5! More than just an upgrade! That's right the E5 is more than just a jazzed up E3! It is in a world of its own your E5 has a higher power output better Signal to Noise ratio and Lower Distortion! The new TI’s headphone amp solution gives an increased sound quality and works more efficiently with high impedance headphones. The E5 is exploding with funky features like a EQ changer which means you can quickly change the sound of your device from flat to having a fantastic switches Bass Boost ! Grab your E5 and a set of headphones connect up your E5 between your audio device and the headphones and your set to experience the ultimate mobile listening experience! Features Designed for high impedance and low sensitivity headphones Easy to carry and use in the outdoors Increases your music player's play time New amplifier IC with higher S/N and lower distortion! Very high PSRR and with a metal case. Reduces the noise caused by GSM mobile phones Individual power switch Electronic volume control ( means very low distortion and avoids the adjustment noise caused by a potentiometer); Two sound effects: Flat and Bass Boost mode Built-in Rechargeable battery gives about 20 hours playtime at normal volume!