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!!

Charged for over a day. Red Charge light on all the time. Disconnected charger, connected audio and headphones. Nothing happened. Totally dead. No sound, no Power light. Tried 2 sets of headphones, just in case. Adjusted volume control all the way. Nothing Got refund.

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

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.

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).

I was also able to use this as a mic amp. The product works very nicely. If you remember the old Boosteroos, it's like that, but just one output, and USB charged. This is a useful little device for the price, especially where one is not sure that this kind of amp will solve the problem at all. If it works, then could upgrade to slightly more sophisticated version for $12 or so... Using this item with phone while listening to mp3, for example, will save phone battery, to last for maybe twice as long.

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.

Work's good. Boosted a cheap headphone. Easy to setup. Down side, crosses the channels from left to right. Not good if your playing video games. You won't know what's left or right.