Spanish band music recommendation

Here's the best thread for comparing portable headphones.  http://www.head-fi.org/t/433318/shootout-95-portable-headphones-reviewed-denon-ah-d1100-added-10-30-11

Of the headphones I'm familiar with, I'd recommend the Koss Portapro, Audio Technica M50, or Creative Aurvana Live!

I'm not familiar with the Ultrasones, but my guess is that they don't meet that thread's definition of portable, probably because of the cable is too long.  If you are going to use them while walking around with your iPod, you probably don't want a cable that will be long enough to trip over.

You also probably should get an all rounder headphone since you listen to a variety of styles.  Most people recommend a very bassy headphone for trance and hip-hop, but that wouldn't be ideal for the Spanish music.  The Portapro wouldn't be too bad for the bassy stuff and good for the Spanish stuff.  The M50 would also be good, but it's closed.  The Sennheiser PX-100 II would be a pretty good compromise too.  The old PX-100 is one of my favorite portables.  The new PX-100 II sounds as good, but isn't quite as comfortable.

Then take a look at the Sennheiser HD595 or HD598.  I own the 595 and like it.   The HD598 is supposedly an upgrade but I've never heard it.

The headphones I use the most directly from my iPod are the Portapro, Sennheiser PX-100, Sennheiser HD595, and Audio Technica ATH-M50.  The Portapro and PX-100 are both inexpensive, open, supraaural (on ear).  The HD595 is on open circumaural (around ear) and the M50 is a closed circumaural. 

I've never heard the AD900 so I couldn't say.  I haven't heard the HD598 either.  I own the HD595 and it doesn't need an amp.  I'd doubt that an amp is necessary for the HD958 either.  Most people think an amp makes the headphones sound better, but most people don't make sure they're listen at the same level with and without an amp.  They're usually listening louder with the amp which makes it sound better.  I listen at fairly low levels to protect my hearing, I listen 6-10 hours a day.  Most portable amps are too loud and even the lowest setting of the volume knob.

This doesn't mean that some amps can improve the sound of even easy to drive headphones like these, it's just that it's not necessary and most amps won't work because they'll be too loud. 

Edit:  I know this is heresy here on head-fi.  Too many people here listen at levels that will damage their hearing in the long run.  Some at levels that will do the damage pretty quickly.