My English is not good, sorry about that.
Prepare to laugh. Today i got my XS and i thought i was gonna be surprised by the sound quality. But i can’t hear ANY difference between them. Same weak soundstage, same harsh treble, bass is almost non-existent.
I think the problem is because I don’t have a dac/amp, so they are plugged directly into my pc (alc1220-vb). I use them on 100% volume but most of the time it’s not loud enough. 990s were good at 70%. Do i really need an amp like Fiio K7 with balanced cable to make them sound at least better than the 990s…? Or all this will just make them louder? Please help :(
Unfortunately, yes you do need at least a moderately powerful amp. Fortunately, once you get something stronger, you will be able to enjoy the lovely qualities of both headphones. I own the XS and can report that it has a fast, detailed bass and lacks almost all harshness (to my ears).
Fortunately you don’t need to spend hundreds of dollars to get a decent amp. First, try your headphones on an amp (friend or at an electronics store). If you don’t have access to either, buy an amp online from a store that allows refunds. If you don’t hear a difference after a few days of listening, return it. When you’re ready to buy something you really want, see if there is a local shop that sells used equipment, check eBay, or buy new.