when i plug in my iPod it wont play without the power being on on the muffs which sucks . When I used the X5 (1st gen) and the xFit, the sound quality rivaled expensive over the ear headphones. My custom orthotics fit perfectly and they are light weight, machine washable and dry quickly?? 4/5 stars because at first I got blisters from the high back. they short circuited on the wire next to the jack where I mentioned there were issues with the casing. I was successful about connecting Bluetooth and initially I tested it out & worked but about 15 min later when I actually wanted to use it, it didnt work. I did not wear them exhaustively but noticed a lot of wear to the heels of the soles (and I am not heavy on my feet). The only part I didnt like is the bright white sole that is very visible from the side. Returned them and very impressed with how quickly I was reimbursed. Directions say to use for 20-30 mins the first few times then go it for a hour, to get use to it. A pesar de que la bocina es pequeña se escucha fuerte y claro, es ideal para llevar a la calle ya que pesa poco, además de que incluye un gancho para colgar la bocina casi en cualquier lugar.