First to clear this up:::For everyone who mentions that they wished blutooth headphones would work with this amp,,they can't work with any guitar signal, ever, at least with current technology due to the delay...yes there are wireless plugs that replace instrument cable but there is no bluetooth transmission that is fast enough...even just a few miliseconds of delay is noticable to your brain when you strum and there is a delay..trust me that you woukd get annoyed with the delay....so accept that there is currently zero way for bluetooth headphones to work with a $40amp....
As far as the amp,,its a $40 rechargable headphone amp with bluettooth stream ability..you cant beat it..for years all we had was the simple Vox battery headphone amps, so these new style headphone amps are a step up...I also have the Boss Go headphone amp which is about 2 steps above this,,but it is also about 3 times the cost...for a simple headphone amp this thing works great..I keep it by the bed to work on my bands songs or youtube backing tracks...you cant expect this to be a concert level tone machine but it does very well for $40....hardwire out to bluetooth speaker and you have a nice mini amp...you cant charge while playing but thats not a big deal...only quirk I found while charging is that sometimes all the effects light turn on with a white glow so not sure what causes that ever so often..nothing in manual mentions it...I have played this thing for about 2 or 3 hours without issue so not sure full battery life...overall for $40 this is nice.