I would also like him to ellaborate. I have to say that I agree with most of what has been said about sound quality here. These are good sounding IEMs, period, and not
good sounding for a bluetooth IEM. I do agree that they have a V shaped response, but they are very musical and the timbre is quite nice.
I find them in terms of sound signature similar to Philips Fidelio L1, with more treble but similar lows and mids. Compared to other budget IEMs like SHE3590 for example, the X7 is much nicer. Jazz trios composed of piano/upright bass/drums on the SHE3590 are awesome because of its very good bass performance, but the timbre on vocals and winds is quite awful (try Zaz,
Ensemble) and as others have said, it does need equalization to achieve a nice overall sound.
Listening to the same music on the Mee Audio X7 Plus, no eq nor anything, instantly put a smile on my face, as there was nothing that I would find bothersome, tiring, irritating or even piercing treble. There is some hissing, from time to time some sibilance, but overall excellent experience, more if you consider the price and that these are BT headphones.
As a side note, I've read that someone said that as a headset there's no difference between using the cable behind the neck or below the chin because the mic appears to be located at the earpiece. I have to disagree, as the user manual and my own experience indicate that the mic is in the volume control.
When I tried a call, the other end would listen only to ambience sound but not me when used this way (behind the neck). When used below the chin, the other end could hear me perfectly (same situation of course, walking in the street), so the mic appears to be located in the volume control thingy, and in my experience these are pretty useless as a headset when used behind the neck (nevertheless behind the neck is the most comfortable position for physical exercise). There's however a respectable amount of microphonics when cable rubs against clothes (no microphonics when used below the chin).
Best,
Bas
EDIT: now that I listen to one headphone after another, perhaps the sound signature is more similar to the HD25-I-II, particularly on the high mids and treble (and it's a more fair comparison, as the L1 is a semi-open design). I just ran out of battery on the X7 plus and as it charges continued listening on the HD25-I-II and my first thought was "the heck, they are pretty similar". Not exactly an A/B testing, but I still got a smile on my face.