I can agree on the PRaT or 'musicality' you're talking about which is often found in Wolfson WM8740, I find similar aspects from IHIFI 760. DX50 does have a sense of forward motion to your music a little like a car that has good momentum flowing down a highway, (foot tapping) however I don't see the point when you're needing to pump the HO amp section so hard you're literally forcing detail out of the player, I had to raise the volume to excessive levels to get vocal detail my Rocco BA can do simply idling at a much more comfortable listening level. You're basically having to listen loud and that's not a good sign.
Often when I see people praising DX50 or calling it a "star" I wonder what other gear they've heard or their point of reference. I'm not trying to come across as pompous or superior though I think anyone who's approaching from an iPod player would be happy with DX50 because they're hearing that resolution I mentioned, which is fine if you want to listen to some clarity that's not a problem. It's little like the Sansa Clip where people immediately hear the clarity jump out at them then instantly think it's better than say player B, Unfortunately there's a lot more to sound quality than a dump of clarity and the problem is DX50 doesn't have much else going for it on a technical level.
The problems with DX50 are the soundstage is congested, (narrow) , it lacks air and has poor separation, when you add all those negatives up in one bucket they form a pretty big problem because congestion and closed in stages cause smearing and a bogged down crowded presentation. .This was overly obvious to me, even my Colorfly C3 has stronger instrument separation and a wider soundstage. So when you add that with excessive volumes it becomes a pretty unwanted listening participation for me, I'm well aware some people are happy with the unit and there's nothing wrong with that, but I will say how I heard it. Maybe my point of reference is slightly different, though after A/bing with the Rocco BA unit I sold DX50 for thosde reasons.
I've mentioned this in the DX50 thread, especially about the separation: If you have an IEM that is capable of strong instrument separation, one that excels in that area or soundstage width for example by using DX50 you're bottle necking the earphone, have a listen next time you use your DX50 and tell me how easily you can make out all the instruments in a busy passage of a song. it might sound ok but I can assure you it can be a lot better. I think we all know your set up is only a good as the weakest link, so for me with my Rhapsodio hybrid I was being deprived of areas I know it could perform because DX50 was capping them short. Connect them back up to my Rocco BA or Studio and V and they came back out of their shell showing me what they're capable of again. I just think DX50 limits what your headphone/IEM perfomance in general.
Don't let this stop you enjoying though.
You make some good points.
I reckon that any DAP at under $300 will have limitations, ie you can't have everything at that price. I AM enjoying the DX50 and it's musicality. Whether I stay with it, I don't know but if I follow the many other audiophiles here, probably not as I search for the ultimate music player !
I would agree that the DX50 doesn't always deal with busy section of music as coherently as maybe it could. Having said that some of the different FirmWares have been better at that than others. It doesn't give me a wow factor in such circumstances, but it does on some slower pieces like an acoustic guitar where the sound can be exquisite. And that what makes me want to come back to it.
My gut tells me that the DX50 is a little better that you are giving it credit for but then again if it doesn't deliver something that is important to you then your view makes sense.