Bluetooth:
On mobile phone easy connection, under Windows 7 I do not get it.
All instruments are clearly audible, no noise. The basses are on headphones regulated, but still very strong.
But in the mobile phone with Equalizer can regulate better since going other frequencies flutes.
With the bass but I get along well.
USB cable to PC:
Super great sound as under Bluetooth - bass there with an equalizer to act better than the phone
I think it's very much depends on the software.
SD card:
Apart from that, all the tracks can be heard only in sequence - of course you can zap back and forth but do not coil - again very good sound. Is peace between songs, you can hear a slight noise.
Here you can also reduce the equalizer bass a bit, but only moderately.
But I must say, on an SD card is on it a lot and I use that often - for example, when mowing the lawn (5000m2).
After a short acclimatization he is also blind to act well. It fits perfectly and wraps ears, looks classy and stable.
On the website I could not find the equalizer file even though it is in the User Guide - a pity!
And that's why there is also a point deduction. I can not stand it when one is what promised and then not kept.
All in all, and especially for a China unit, there is no alternative for bass lovers in this (and higher) price range.
Well, I is not known.