They are double the price though! :p But yeah, whatever suits your needs :)
I'm waiting for the PA2V2 amp to pair with my SGS3 and the M-100's, so I can't wait to see how that improves things.
It's meant to be less analytical than the O2 amp, but it may give it a warmer sound which may appeal to me.
You'll find a lot of her stuff sounds good on the M-100's! :p That track is really good though!
I am one of the latest victims of this site's motto - initially thought the $300 M-100s was a reach! What I learned from the M-100s is that ultimately, it's what your ears think of the sound that matters most. Ultimately, one of the reasons I sent back the M-100s was that I didn't want an amp for something meant to be portable. The O2 amp, while portable with battery, is a bit bigger than others out there. I'm thinking I'll stick with IEMs for portable, at least for now.
After owning the QC-15s, I really appreciate being able to turn the phones sideways for portability. I don't mind height, but bulk made the M-100s harder for travel with my laptop case, even though they were very compact overall.
I found the M-100s very uncomfortable. They really hurt my ears. I forced myself to wear them for hours on end anyway, even sleeping with them. After a few weeks, they did get much better to the point where I didn't mind wearing them at all, even feeling comfortable.
My ears touch the inside of the driver enclosure making the outer tips of my ears red and painful very difficult to wear for long periods. I am thinking of returning them. What a shame, I heard about the bigger pads coming out, I'm trying to decide if I should wait on those.
My first impressions running out of a E10 is very balanced sound, I can't find anything I don't like about the signature. I demoed both the HE-400's and the M-100's. I liked the M100's more because the music felt more engaging and there was a stronger bass punch. The HE-400's sounded airy, laid back, and distant. Did not like. I tried the HE-400's out of various amps including a tube amp in store.
I listen to EDM exclusively though. I owned the D2000's and Pro 900's before this, the M100's are just about as amazing as the D2000's
I've never heard the HE-400s, but do own the HE-500s. I found the bass punch on the M-100s to be very similar to the HE-500, but the 500s went much lower. This was unamped, so can't wait to pair it up with SR 71B, which is supposed to make the bass sound even better. However, HE-500s aren't really portable. It was WAY more than I'd wanted to spend on headphones, but I am thrilled with the purchase and have no regrets. That's not even accounting for the expensive amp and now the balanced cables I'm about to order.