Thank you for your reply. I was very busy today, and I apologize for the delay in my response.
So if you know what you like and/or don't-like about it, you can compare the frequency response to other headphones reviewed here.
In fact, when connected to the M2s (Shanling M2s), I thought the X2HR sounded quite good—
full-bodied with decent detail. However, its
vocals and bass sometimes felt somewhat recessed (especially the bass), and the
forward-facing sound seemed somewhat missing; it felt like I rarely heard any sounds coming from the front. When the X2HR is
connected directly to the computer, many details are lost, likely due to the
poor performance of the computer's DAC chip; the low, mid, and high frequencies all become
flat, and then the issues I mentioned earlier (the recessed vocals/bass) are
no longer very noticeable.
That's tricky. It turns out that "soundstage" is also influenced by frequency response but you probably don't want to sacrifice frequency response for soundstage. It's also (obviously) and illusion. Most people don't perceive a realistic soundstage and it's very common to perceive the sound coming from inside the listener's head!
Headphone soundstage survey
Yes, that's right. I'm
unwilling to sacrifice soundstage for frequency response; I believe
frequency response is the most important factor.
I looked at the 'Headphone soundstage survey' post you mentioned, but I find it hard to judge whether I can perceive a realistic soundstage because I have used very few headphones. However, I can definitely feel sounds coming from
inside my head (left, right, and between them) and
behind my head (left, right, and between them). The area
in front of my head seems less obvious, I'm not sure if this is a headphone issue.
There are also other factors such as comfort (which is "personal") and preference for open or closed back, etc.
I prefer
open-back headphones. Although they don't have good isolation, the
soundstage is generally better and the
bass is less likely to feel boomy or congested. Comfort is not a primary consideration for now, unless it is ridiculously uncomfortable to wear.