With the bass, you'll be exchanging quantity for quality. It will sound more tight, controlled and appropiate, at the cost of boomy and overpowering bass. I can easily listen to some light dubstep and not notice a lack of bass, but in the beginning, you'll have to adjust from the HTF600's sound signature.
For Rock, Orchestral and vocals, it's absolutely amazing. Compared to the HTF600's, it'll be better by leaps and bounds, and you'll probably start to hear instruments you've never heard in a song before. This is due to a wide soundstage the 598's have, which allows it to play instruments from where they were actually recorded. From a deep bass rumble, to slight tambourine shakes in the distance, you'd be amazed how many instruments some songs use that you didn't pick up on. For instance, on a specific instrumental track, you can hear a very low rumble. At first, I thought it had to do with distortion from the track, or that my headphone's drivers were faulty. Later, I found out that the sound produced by a Chello being played very deeply.
I sometimes come across a really good instrumental track (LOTR OST, Mind Heist, trailers etc.), and occasionally I just smile out of the sheer enjoyment of the sound that the 598's produces. It's when I enjoy music the most, frankly. Just make sure that the source material is decent (I recommend 320kbps) Youtube uses 192 at the highest setting, and I can definitely hear the difference between 320 and 192kbps.
For entertainment, the wide soundstage really gives an edge to the sound. If done properly by a game/movie, you'll be able to clearly hear the direction and distance of a sound played. On occasion, I had to pause the film and make sure that it wasn't actually coming from my surroundings, no joke.
I'd suggest looking at Amazon, as they're only 157 pounds right now. Try and stretch your budget a tenner or two more and get the FiiO E10.
If you do decide with the 598's and receive them, I'd be delighted to hear your first impressions and questions in a PM!
I'm sold then once I sell my old graphics card! Thanks for the effort to write your opinion on them.
Yeah, what you mentioned with the genres are exactly what I listen to. I've never been too big on spending a lot on headphones so thought i'd treat myself. I can't imagine how great the soundstage will be as sometimes on my HTF-600's, I sometimes think some sounds are around me; only occasionally though.
Are the problems with the headband cracking fixed? My current HTF's also had a problem with the slider adjuster coming lose and now dangling by wires, how durable in comparison considering it's plastic as well? I'm more likely to take care of these more.
What's the difference between the FiiO E7 and E10? How better?
EDIT: Why is the E7 £64.75 on Amazon and the E10 is £61.98? I'm not familiar with headphone amps. My sound card is also an ASUS Xonar DX too.