This pretty much describes my M-30s. The warranty is great, so when I accidentally tripped and broke the 3.5mm jack off of mine they repaired it fast and for free. The only real problem with mine is that like yours they do leak a lot of sound, and they are a tad underpowered. I often find myself having the volume on max to hear my music well, but it's still within reasoning so I don't mind.
The M-30's have a impedance of 65 Ohms. If you've had physics at school then you probably recognize the unit Ohm for resistance. Basically, the higher the impedance, the harder the headphones are to drive. Lower impedances can be driven by any mobile device, while higher impedances require an amplifier to give the best sound. Some headphones have a whopping 600 Ohm impedance, meaning they are completely silent when hooked up do a mobile device.
The 65 Ohms of the M-30 don't seem that high, seeing that my Porta Pro have 60 Ohms and work flawlessly on any mobile device. Do you hear any difference when listening to them through the computer? The sound chip on your motherboard should help performance a little bit. Or maybe your headphones are harder to drive than mine, for some other reason.
