List of stores in Korea for audiophiles! And my impression on few of them.
Schezde. Located in Cheongdam dong, Gangnam. It is very close to my house, so I walk down there few times every month when I'm home. Premium store with very nice interior and wide range of iems/hps. It is also quite in there and the staffs are trained(at least better than other stores I've visited. they know some audiophile stuff). I liked TH600 and HD800 from their store. They also have a high end speaker section, so it's definitely worth checking out.
http://www.schezade.co.kr/
Earphoneshop. Located in Haehwa. Probably most famous store in Korea, but I prefer schezade for full size hps. Earphone shop has lots of iems, as the name suggests. They even have a Rooth booth, so you can demo customs too. Not too many high end hps, but they do have some. Ran by EXS, and if you are looking for an Korean iem, you are likely to find them here. I bought my H-200 here for a good price. It doesn't feel as luxurious as Schezde, but if you are looking for mid-high range iems, this is a good place to start. I liked K3003i the most in the store. They also have hifi man orthos unlike schezde.
http://earphoneshop.co.kr/
Sony IEM Store: Was located in Coex, It had lots of iems, but closed for renovation.
Sony Store Coex: Although the iem store closed in coex, I think the "official" Sony store is open. It's located on the ground floor of Coex. They have all of their full size flagships, but don't have EX1000 and MDR7550. MA900 and PHA-1 was my favorite. They also sell camera equipment, audio recorder(pro), and computers.
a# Coex: a# is a name for apple retail stores in Korea. All a# has pretty good line of hps and iems. a# in Coex even has SE535 and high end FAD iems.
Kukje Midi: IDK much about the stores. I've heard people saying that they are a good store. They import lots of international gears.
Headphoneshop: A store near Ipark mall in Yongsan.
Technomart! This is old shopping mall built for technology stuff. Although half of the building is empty, they had few good stores in them last time I visited(about a month ago). You can also bargain the price a bit and get some custom made stuff there. Interesting place. Go quickly as the mall is starting to fall apart.
Tell me if you know of more stores in Korea.