As part of my Sony MDR-Z1R impressions, I compared a range of music players too. Thought the findings and opinions might be pertinent to this thread too.
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http://www.head-fi.org/t/818846/the-official-sony-mdr-z1r-flagship-headphone-thread-live-from-ifa-2016/2925#post_13051802
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Comparing the Music players.
A brief breakdown of what I think might be the sonic differences between the music players based on some extensive comparisons pertaining only to use with the MDR-Z1R's, using the X-DAC/O2 and Fostex HP-A4BL. I try not to use the V200 for these sorts of tests, because I do believe the V200 is ever so slightly coloured, whilst my other equipment is not.
To add to that, memory mode was used with each player, however upscaling was turned off. Realistically I don't want software approximating what I should or shouldn't be hearing, based on phantom algorithms.
Amarra - Miniscule sub(?) bass and upper mid extension. Isn't really a good fit for the Z1R's, as it make's things sound ever so slightly more congested, and vocals a minutia less realistic and more thin. When using Amarra, you can actually press a button to switch to vanilla iTunes instantaneously, and I actually prefer the sound of iTunes vanilla to Amarra mode with these headphones. With the T1's and HD800's, it's the polar opposite.
Pure Music - Sounds leaner and very slightly more detailed than the others. Not sure why. Maybe ever so slightly less bass? The bass does sound a touch more detailed or defined, and I do find it a little bit easier to separate instruments and sounds. The negative is that music can sound a tad less engaging and fun. On the plus side, vocals still remain honest sounding, if at times a micro bit more distant. Use this player for when a track sounds too dark with the Z1R's.
Audivarna Plus 2 - This is a weird one, because the Integer 1 and 2 settings actually sound marginally different. Integer 1 sounds very slightly more detailed and spacious, but at the expense of engagement, and a teency bit less honest or accurate vocal tones. I believe Integer Mode 1 has a touch less bass, and thins things out just a bit. Integer 2 sounds the most accurate and honest of the bunch, but is a slightly bit warmer. Overall this is my preferred player for the majority of stuff with these cans. I switch to Pure Music when I want that teeny bit more flatness and neutrality, but otherwise I generally stick to Integer mode 2 (or 1) with Audivarna. Ironically this player and mode is actually the closest sounding to iTunes vanilla, but unless it's placebo, I do think Integer 2 Audivarna may still be a morsel less hot up top than iTunes vanilla, and a touch more dynamic too, but I haven't done enough comparing to know for sure.
iTunes - As above, essentially sounds the same as Audivarna Plus 2 set to Integer 2, however I do find that highs can get a tiny bit more flustered with iTunes. Not sibilant necessarily, just not quite as smooth. To re-iterate though, I haven't done enough A/B'ing with iTunes and Audivarna to state this with any sort of conviction, though I have done a lot of A/B'ing comparing iTunes with Pure Music and Amarra.
I also haven't done enough comparisons with the mobile music players yet, but unless I'm going crazy, I do again believe there can be a sonic difference, depending on how you have PowerAmp set up. I think DVC with PowerAmp adds some sub bass presence or something. In the description it mentions that this mode "improves dynamic range", whatever that means. So maybe it really is adding a very slight colorisation. Suffice to say, I turned DVC off. In-fact I've turned everything off on PowerAmp. DVC, Tone, Limit and EQ. I'll do more comparisons between vanilla PowerAmp and Samsung Music player, but with everything on PowerAmp turned off or set to vanilla, I believe they sound pretty much identical, and based on preliminary comparisons, essentially also pretty much the same as Audivarna Plus 2 set to Integer 2, and iTunes.