Yep that's all I use.
Is scanning the USB OTG a possibility? I just picked up a 128GB flash drive and a USB OTG cable. When it's hooked up I can go to the directory and choose USB OTG but there doesn't seem to be an option to scan it in. It's nice to have 192GB of music at your fingers though.
From what I know, no you cannot... the workaround I've come up with is to organize the music I intend to use on the DX50 differently, and put it in just a few folders (I usually use an Artis==>Album folder structure), with all songs together. Then I navigate Directory==>OTG==>folder, select a song, and the DX50 scans the ENTIRE folder and adds it to its database (doing this for every Artist==>Album folder would get old VERY fast, which is why I do things differently for what I want to use on the DX50 through OTG). On the 32GB microSD card I connect through OTG I use just 2 folders, so it's not a big deal... it takes a little time to scan each folder (there's about 400 songs in each), but then it knows them and you don't need to scan again (as long as you start the DX50 with the scanned OTG "whatever" connected... if you start the DX50 without it, it will realize that the OTG music is not there, and will delete it from the database, which means that next time you will have to, again, navigate to the folder to add it to the database). All this because I like to listen to a big collection on random... if, on the other hand, you want to select a specific album, it's better to organize everything by an Artist===>Album folder structure and simply navigate to the proper folder.
Yep that's what I've been doing.
Ummm, someone also commented on this previously. It turns out he was literally trying to pull out the card, which is not the proper way to release it. You have to push the card in the slot to release it and a spring mechanism pushes it out of the slot. This is pretty much standard for card slots. FYI, if you are doing the same thing.