The DX90 sounds great, almost equal to my DX100 for half the price....but I'll start with some operational issues I've had:
1. Some folks, me included have had difficulty with the DX90's media scanning function not properly building the library and/or resulting in all files tagged as "null". These same files work great on my DX100, so it appears to be a firmware issue.
Despite one recommendation to cut all of your tags down to barebones...try this first.
After experimentation I recommend the following to anyone having trouble with media scanning. Put your micro sd card in and do a scan. Leave it alone! It may seem like it locks up, and it is definitely taking longer than it should, but eventually it will clear. Once done, look at your files, in my case they are all shown as "null" and cannot be accessed via "all music" or file directory view. Do a factory reset. After this, every time, all music is still hosed...but now you can go to directory view and select a song from any folder you have. Once you do that it will do a quick scan of all the songs in that folder, and they will all work correctly and show in "all music" etc. At least I can use it now...but I have over 500 folders....doing them one at a time does not sound like fun. (Edit: Periodically, when the unit is turned on, it will do a media scan even when there are no changes to the storage card. This is frustrating as, due to the media scan lockup issue, the device is unusable for up to 45 minutes until it finishes.)
2. Another issue is that the DX90 will occasionally not show correctly in usb connect mode. It shows the internal memory and the sd card as removable drives, but in the case of the sd card it does not recognize the drive size or label. Usually dismounting and remounting will fix this, or another factory reset.
3. UI is generally OK. However there is a 2-3 second lag of response when operating the unit's front three buttons.
4. Scrolling is a little touchy, and sometimes a little difficult to find/select a single track in a long list due to brief lags.
Edited by wolfen68 - 4/22/14 at 2:53am