Recently, I purchased a Zune HD 16gb. While I love the UI and build of the zune, the volume feels far too weak. Previously, I was using a iPod Classic 5th generation + Koss Porta Pros, which, while sounding a bit muddy at times, were always loud enough using maybe less than a quarter of the volume bar. The iPod was even able to power my Senn HD 598 quite well. Unfortuantely, the Zune has trouble even powering my Porta Pros. I need to raise the volume up to nearly 13-15/30 to listen to music on the porta pros. Understandably, the HD598s require 20-23/30 of volume. The only reason I bought the zune was due to better sound quality of it. I realize an portable amp might be the solution, but I was wondering what would be enough. Would the FiiO E3 work, or would I need something like the Fiio E11? Thank you for the help. P.S. Totally unrelated, but would the Sony A series walkman able to power porta pros well?