MobileSpec Headphone Amplifier & Enhancer for Universal/Smart Phone, Black

This thing is awesome, very handy to have to boost the signal from my Xbox 360 e audio video cable, I connected a 3.5mm male to female rca adapter to the Audio portion of the AV cable so I can use headphones with the system. before this adapter the audio was very weak but this gave a very good range of volume control for my purpose, thumbs up!!

First of all it does not amplify the sound. It attenuates it.Second, I was charging it for 3h and it did not charge. When you disconnect charger it dies.While charging it gives the high pitch sounds and is impossible to use connected (e.g. for TV) all the time.

The product works great. Although it cannot work with my newer ph one the does noy have an physical audio output, no bluetooth I still would buy it again because All my computers tablets and older phones do have audio output via and audio output port, Some of my computers and tablets and older phones the do not have adequate audio, do have an audio out put port but not enough volume. This device is perfect for those devices. Note I have 4 computers 3 tablets and 5 phones

I've had three out of four with bad batteries so far this time around :-/ .I have one I bought last year and one out of this batch that works fine so I know it's not me.I have some 32 ohm low sensitivity headphones (Planar Magnetic) I wanted one for but it distorts horribly even at low volume. But it sounds great on my 60 ohm headphones (Dynamic).

This item does not work unless you have power applied to the USB port. Once it's unplugged, the unit turns off. The other major problem is the constant buzzing all the time. The item is useless.UPDATE: I decided to open the device (and ruin the warranty) just to see if I can find something obvious since I can't imagine someone designing something this bad (I'm an electrical engineer). I found that the battery was puffed up. I unsoldered the battery and tested it to find it was completely bad. I soldered a new battery to the unit and now it charges fine and the buzzing noise went away. It works great. I would have given it 5 stars for sound quality but I don't think I should have needed to do this. Also I would have rather had an on/off switch instead of needing to plug in the headphones to turn it on.

This is a great little amp. I'm using it for my phone that has low volume and works like it should. There is no power button, in which plugging in your 3.5mm output jack turns the device on and unplugging it, off. It's very compact and serves its purpose well.

This device is not an amplifier and should not be advertised as one. It can REDUCE the volume from the source, but it will not INCREASE the volume. Buy this ONLY if you want an external volume FADER -- though I'm not sure why anyone would want that. Mine went right back.

I purchased this to use on my motorcycle to increase the volume of my helmet speakers. It replaces an older unit that is about three times the size and uses AA batteries, which is inconvenient. Volume and quality is about what I expected from an inexpensive unit. Size is great and the ability to run it on USB and/or battery power is a big plus.