In the end I had decided to steer clear of buying a set of MDR-MV1's despite how good they seem and instead stuck with my original plan of buying a set of ATH-R70x's over the HD600 or Sundara, these 3 seem to be just picking your poison of a different flavor. I found a set for sale for extremely cheap in new condition down at a flat $200 from its $350-400 full price tag which I was also able to find a good amplifier to pair with from the money I saved and settled on a Fiio K7 also on sale, No regrets after switching out cables, it fully transformed the sound of the setup from great to fantastic.
The reason I didn't go with the MDR-MV1 is because I found its response (based on peaks relative to semblance I typically have issues with) to be too similar to my Moondrop Katos, in that is boosted in bass and treble, which I myself still have wanted to dial back because I want a more mid focused headphone which is exactly that the R70x is. It must be my ear shape or size because I seem to be prone to semblance issues and is the main reason I don't use some headphones/IEMs and just didn't want to take the risk with a repeat of my moondrops.. Dynamically the R70 doesn't have the extended treble like the HD600, but what it just has is silky smooth mids of a different flavor, excellent imaging, with about par sound stage, and a better low bass response. Although I could just be lucky because I am in he group of people that don't have fitment issues, my ears don't even touch the cups because they are so small as a result I don't get as much of a one dimensional sound as others claim to have experienced.
Switching cables has also surprisingly helped after getting a good quality 4.4 balanced cable to run with the headphones. The new cable requires significantly less power from the amp to reach loud volumes, for whatever reason almost double the output of the 6.35->3.5 jack (from factory). The treble and general dynamics also sound far extended so who knows what thats about. This is by far the biggest impact Ive had a cable make in terms of sound. whereas the factory cable sounded somewhat dull, warm.
Now here's the main reason I'm writing this post. This setup sounds full on spectacular... off of desktop. All frequencies are accounted for, everything sounds balanced and as it should, its so good I just don't even need to question it. Every song, Every genre sounds like I'm hearing it for the first time and rediscovering music. This is the all-purpose headphone I was looking for. This is the home setup I wanted, but it isn't as pretty for the Walkman. I mistakenly found my desktop setup despite purchasing for the WM1 and im definitely not sending either of them back.
It isn't a loudness problem. It gets even louder than my desktop does, but across every tuning, every region, no matter how much power it is given, some frequencies just feel not well represented, it loses some of that choppiness and clearness that was present on the desktop and just like that fullness and warmth is lacking. It still sounds very good, it just isn't quite on the same plane.
So my question is.. What are the effects of the NP Audio mod as far as this? Can it clear everything up and make output cleaner like it sounds on the desktop? Or would this be caused by a lack of power under some frequencies due to impedance shooting up to some staggeringly high numbers (nearly 1000 ohms! at some point despite its 470 ohm rating) that the Walkman just cannot deal with?