Pros: Powerful clean audio with good portability and build quality
Cons: Takes quite a while to charge (3+hrs) and can’t be used while charging. If you have a decent portable player, you may not notice an improvement.
This is primarily designed to amplify sound out of mobile devices that do not get loud enough for you, either because they are low quality, your headphones are not sensitive enough, or you’re going deft :). As a bonus, it has a built in bass boost with 3 settings (off, 1, 2). It also has a good quality easily replaceable Lithium Ion battery (BL-5B), and comes with the mini USB charging cable and 3.5mm to 3.5mm audio cable. Also in the box are two silicone bands of different sizes to attach the unit to the back of your mobile device.
The unit has 2 LED lights, a blue one that comes on when powered, and a red one for charging. The power switch is built into the volume knob. You know it’s charged when the red light goes out. For those who plan to use this as a laptop or desktop amp, note that it cannot be powered on (blue) while being charged (red). It also has a high/low output switch.
The unit is surprisingly small and light, especially considering the power output. It is well-built with high quality plastics. The volume knob is metal and requires a good amount of force to move it, and I never had a problem of the volume changing while in my pocket. Battery life for me was between 8-9hrs average, but varies based on volume. Giving it 9/10 because it could still be smaller, and the mini USB port is being replaced by micro USB now as the standard. It would also be nice to use it while charging.
Sound wise, it does what it’s designed to do exceptionally well. It’s mainly noticeable due to higher volume, but the bass boost works well, and it gets loud and stays clear without distortion all the way up. I did not test the AMP with high impedance headphones, I only own moderate to low ones myself. When connected to my Galaxy Nexus phone, with various headphones (Q350, HD-25 II, SR60i, HD558) the difference was night and day, but mostly due to the lack of power output of the phone. Bass boost is nice to have on mobiles that don’t have that built in.
However, when connected to my Sansa Clip (Rockboxed), I couldn’t really tell the difference when listening at my usual volume. That being said, the Sansa has plenty of power to drive any of my headphones to satisfying levels. I never really go beyond -12DB volume on the Sansa alone. I also found the bass boost less satisfying than using the built in bass adjustment on the Sansa. I still give it 8/10 because it does very well for poor quality sources like phones.
If you already use a decent quality portable that gets loud enough for you without distortion, and has built in bass boost or bass/treble adjustment, you will not notice much improvement. If you plan to use this as a desktop or laptop AMP, look elsewhere because you can’t use it while charging. If you have low sensitivity headphones you want to go portable with or you have a portable player that does not sound good or loud enough (like most phones), you will love this product. If your deft or like to crank volume in general, I highly recommend this. In my personal case, the Sansa is more compact to bring along with my Phone than the Fiio, but I still use the Fiio when my Sansa dies. So I still find it useful. But keep in mind the Sansa Clip is under $40, so it presents a cheaper way to get better sound on the go. Because there are portable players that are much smaller and produce comparable audio for less, I give it 8/10.