Need help on sennheiser headphones...

Hi. I need help deciding on headphones. I'm thinking of Sennheiser pc350 and sennheiser hd555


PC350
- closed headphones
- has mic
- some forums say that it uses the same drivers that of the hd595 (which is better than the hd555)
- i haven't tested it because i'm from the philippines and we don't have it here. i'm going to buy online (ebay)
- it has 150 ohms impedance which could be a problem.

HD555
- open headphones
- we have it here and I have tested it, I loved it but it's expensive here
- doesn't have a mic
- can be used with ipod because i tested it with an itouch.

My questions are:
1. with 150 ohms on the pc350, can my Xonar dx drive it to its full? if not, can it deliver acceptable sound quality without an amp?

2. also, can i use pc350 (150ohms) on ipod? i think it will be too much for the ipod to drive isn't it?

3. which is better? music? movies, positional sound? gaming?

Thanks!

There is a significant difference in sound quality. I find open headphones to sound clearer and more detailed. Closed headphones tend to have significant advantages in bass though. I prefer the sound of open headphones, though closed can definitely sound quite good. Personally, between those two, I'd go with the 555, but either one is a great set. If you want a mic, that's a strong point in favor of the 350.