First: I love my iMP-550
I have to say I was not totaly impressed a few hours after opening the box, but to establish a loving relation takes some time. Now, after over 50 play hours I am very satisfied.
One extremely good think which is not related to the physical player itself, is the support iRiver does to its customers. Some says companies which releases firmwares often did a bad initialy job, but this player has in fact been extended with new functionality in several ways after the release. Sony, are you listening?
Xtreme 3D is good, but when listening to some live recordings it seems to do something half-ugly to high frequency sound. But the sound becomes much "bigger" with this new addition.
Even this is the best portable player I have had, there is a few problems I have found:
1) When the player is connected to the charger and then I changes something in the settings menu, the settings are lost if I just disconnect the charger without first holding down the Stop button. When the player goes into sleep mode after inactivity, this is not a problem.
2) I have problems with several CD-Rs burned as Audio CD, all burned as single session. When I got the player, I switched off multisession so it would load faster. But it seems it will read some of these CD-Rs incorrectly when turned off, skipping between tracks and track times are incorrect, and the disc takes really long time to load. Switching on multisession corrects this.
If I lower the burning speed, the error is less likely to appear. I am using Verbatim 48x discs which are burned on a Yamaha CRW-F1 at 44x, lowering to 16x is better. 44x is fast, but this disc/burner combination has had very good burnquality at this speed. The strange thing is that all the other players where I have tried these discs has played them perfectly, even over 10 year old standalone players...
3) The amp is to weak when the recordings have a low recording level, but that I guess is how it is today. Maybe I need to buy an external amp....