[CAfromCA]

I currently have MOTU Microbook. I also have 2 sets of headphones, AKG701 and Sennheiser PXC 450. I tend to use the Sennheiser when there is noise in my area. I am listening to what is often badly recorded speech. I am looking for clarity and sound as close to the original as possibly, although I sometimes need to adjust levels to hear better and try to remove background sounds. I don't need anything fancier than a graphic equalizer. I like both of these headphones, but the audio is very quiet and I can't get the volume up. I guess this is due to impedance, but that subject just makes me tired. Can anyone recommend a headphone amp or other equipment that would help me? I am using Windows 7 Ultimate, Dell XPS9000 with a terrible Realtek sound card that I disabled for the MOTU. Thanks for any suggestions.