Thank you for your advice RMSzero! I live in Glen Allen. I'm afraid I have no spare time to go to Washington D.C. this Wednesday. It's really a regret I think it will be a wonderful trip. Maybe I will choose the 497.

After "studied" several months. I decide to buy one Grado's sr60 or Sennheiser's HD497. All reviews say they work well with portables. But I still need to make a decision: which one? I think I need to have a try before make the final decision. Now I work in Richmond VA. US for a short period...