The EX71s are very good for what they are ($30 earbuds). They're my airplane headphones of choice. Comfortable, efficient, good isolation, and if you forget and leave them on the plane, you don't hate yourself.
I also have 10 yr old V6s I just recabled. This made a remarkable improvement. What I did was replace the coiled cable with a cable I made from cat 5 wires (not jacket). 2 pairs, cross plyed on my wife's spinning wheel. I then used silver bearing solder and a cheap gold mini from radio shack. The highs are a little better now, and that awful coiled cable is gone. I swear I can hear the difference between the left ear and the right now (I didn't replace the cable connecting the two sides). I'm tempted to drill out the left earpiece and go to a split wire configuration. This was my first custom cable configuration, took about 45 minutes, and cost nothing for the scrounged cat 5 cable, $3 for the connector, and probably $2 for the techflex. The V6 is a standard for a reason. They're not the perfect headphones, but I think they're about as good as you'll find under $100.