You're in a tough spot, since MDR-7506 aren't bad headphones to begin with, at least based on measurements.

I haven't heard those, but it seems they have decent bass boost that doesn't bleed into the midrange, no excessive warmth, proper ear gain with maybe too much upper midrange and treble. It's all going to be "same, but different" from now on, especially if your friend already seems to have this attitude:)

I've had an occasion to listen to a Stax SR-007 (first version) and I wasn't blown away. I didn't hear all the detail or resolution I expected, based on what you can read online. Sure, they were sounding good, but that's it. No mind was blown. I'm more impressed by my Samsung Buds 2 since do seem to over-exaggerate detail (8 kHz boost) while still having a pleasant tonality overall. And I'm lucky to be one of the people who does experience soundstage in IEMs, at least with the music I listen to (soundstage is very dependent on the recording, though for may people IEMs will always sound closed-in).

I suppose if you really want to blow minds, for $200 you can get a pair of decent monitor speakers (JBL 305, Kali LP-6) and some good weed :) (if you don't have moral objections, legal issues with that in your country and no mental health risks like a history of schizophrenia or depression in your family, of course).

EDIT: Looks like a pair of JBL 305 is $300 and not $200.