The issue with the DBA-02 is not in the highs but rather the lows. It's simply that the low frequency driver used can not really match the aggressiveness and presence of the high frequency driver. It has a similar kind of speed and presentation, but it doesn't quite match the output of the high end. The low frequency notes are simply too short and end up lacking body and presence. The low end sounds lean and unfortunately starts way up in the midrange and all the way down. The DBA-02 is a good earphone, just not quite the godly thing it is made out to be. From a personal standpoint, I would rather use the RE-Zero. It doesn't have the speed and aggressiveness of the DBA-02, but it's better balanced and even. Notes are more natural in presentation and lower frequencies carry better body and texture which helps fill out the lower frequency sounds better. The DBA-02 is an excellent analytical tool, but from a casual listening standpoint, it can be a touch aggressive. As well, the short note with a significant lack of texture and decay does cause problems in presentation of sound. It ends up lacking some information, and this is unfortunately common among many BA based earphones that aren't geared towards a thicker, more moderately presented note. A better filled out note means more information, regardless of speed. I would be more inclined to suggest something like the ER4P rather than the DBA-02 for this reason or simply step to well balanced and capable dynamics like the RE-Zero or RE252 if you want something more aggressive and detail abundant like the DBA-02.
This is your set of critera:
- Great SQ (ofcourse, haha)
- Good for rock music
- Clear vocals, guitar, drums but not immense much treble (a good balance)
- A nice round bass that gives a good "boom" but not huge
- Also good for hiphop, metal and classic music. (So, all other genres)
- Does not need an amp for best performance!
I'm not sure what you're used to, so I can't really say how good of SQ is required to actually impress you. If you've come from crap, it's not hard to impress. A good mid level product will blow you away. However, if you know your stuff, it may take a slightly more serious product to really impress you.
What's good for rock music? That might be a bit of a personal preference, as in how you prefer to hear your music. In a basic sense, you have vocals, guitars, drums, cymbals, etc. that need to be decently presented. Overall balance may or may not be all that important. If you're a drum guy, you may want the drums emphasized a little. If you like guitar riffs, you may focus more on the mids or maybe the midbass if you like the bass guitar. Maybe you really like to hear the screaming, edginess of the guitars, and the cymbals crashing. The highs may carry some more importance. At the very least, a well balanced earphone will be good in a general way. Personal preference may reshape that a little bit towards a little extra bass, mids, or highs, and you will have to decide what you want for that. You do say that you want a good balance overall, so my guess is balance is more key than emphasis. You pretty much want to hear everything even in presentation. You also make extra note for good bass presence, not amount, and that the highs are there but not too much. This hints at least to me towards an earphone with a thicker note, something a little smoother and full-bodied.
Bass can be many things and depending on earphone may not be certain things. Boom implies some heft, body, and good presence. You don't get boom without weight and authority. If the earphone rolls off on the low end, is too lean in note, or lack some dynamics on the low end, you may be out of luck here. You don't sound like you're a bass head, so I'm guessing you don't actually want a lot. It's simply that you don't want lacking. For that you will want to avoid earphones that roll off early and earphones that lack note thickness. It will be preferable to pick options that have a thicker note with more decay and texturing. You want that kind of presence.
Many earphones do fair well without an amp. Many do benefit to some degree with an amp, but the need and level of improvement depends on the source player. If the player is weak, you may have some shortcomings in terms of loudness and control in the bass. Even a small, affordable amp like the FiiO E5 can become helpful. However, if the player is a competent device and you don't listen to your music at high volume all the time, then amping will not be all that needed for a majority of the products out there. For the most part, you simply avoid products that have a high ohm load, and that's pretty easy to do.
Earphones that I've used that come to mind with this information is the RE-Zero, Custom 3, e-Q7, and MTPG. These carry good balance overall, good note body and weight for the low end, extended treble but not dominant. The MTPG is the heartiest of the bunch, thick and heavily textured. Treble is smooth, bass is well controlled. The only shortcoming is that the earphone is a little sluggish. It gets slightly muddy with complex stuff but sounds great with simpler music. The Custom 3 is one of the few BA based earphones with a thicker note but this is dynamic, textured, articulate, and simply well done. Low frequencies carry a lot of presence and energy, mids are well balanced, highs are smooth yet energetic. It is unfortunately discontinued and now very pricey, plus the cord is very crappy and a problem point for the product. The RE-Zero is more mild-mannered. It's actually slightly aggressive but natural and playful. The presentation is clean and light. Bass is only slightly lean with a little roll off but not all that much really and still offers good bass punch but maybe not as much thickness as you may seek. The e-Q7 is the better mix of everything. It's well balanced, has a thicker, textured note but is very clean and quick. Treble is extended and detailed but mild. Bass carries good extension, note thickness, and heft. It can be deep and authoritative if the music calls for it. I kind of see the e-Q7 or MTPG as the two better options for you. The e-Q7 is the lighter and quick option while the MTPG is the more thick and robust option.
That's the way I see it anyways.