I've used my Bravo Ocean from iPhone/iPod headphone jacks, from 30-pin ports with FiiO cables and 30-pin to Lightning adapters, from the output of DACs like the Dragonfly or Microstreamer, etc. All work similarly for me, with a great smooth sound that's definitely an improvement over an iPhone, iPod, or laptop headphone jack. And mine is never muddy or any of that - I get good detail in the bass as well as in mids and treble. It's pretty remarkable for the price. I have several SS amps, like the Portaphile Micro, Decware Zen Head, several FiiOs, Oppo HA-2, etc. This one is right up there in sound quality, although I must mention I run mine on top of my Macbook Pro that's closed up - a large flat aluminum surface that absorbs and sheds heat, so the Ocean doesn't get too hot. Too much heat and the tubes suffer.