If you're going with the X1, being an open back, there's some things you need to know: bass extension is weaker, bass can get a bit loose at times (Q40's bass is tighter IMO). Apart from that they're excellent cans that are an upgrade from the q40's in terms of timbre, soundstage, smoothness and fun.
BUT, if you're looking for quality bass, then why don't you check out the HE-400? I'm surprised no one mentioned them yet..
BUT, if you're looking for quality bass, then why don't you check out the HE-400? I'm surprised no one mentioned them yet..