Have you ever tried HD 558? Do you hear any more grain or distortion with 518 vs 598?
I remember when I first tried the HD 518, I also briefly tried the HD 558 and it sounded off to me (thin). Can't remember exactly what it was. I was in the showroom mainly for the Momentum and FiiO X5, there was a wall of headphones, and I briefly tried The old and the current HD 5xx line.
I just remeber I didn't like the HD 558, HD 559, HD 569.
I liked the HD 579, and HD 599.
I was surprised, and liked the HD 518 that sounded similar to HD 579 (but that was in a hurry, probably the HD 579 is better).
Last night I compared my 518 and 598 SE side by side.
The bass in 518 is much more elevated, but too bad this is mainly in the mid-high-bass zone, and with some songs can produce a less correct tonality of the snare drum and toms (a bit boomy). Maybe at very loud volumes with bass heavy music (hip-hop) it can distort, but I didn't hear any distortion at medium-high volume with pop and rock. Also the bass is more enveloping, maybe it bleeds some into mids, but to me it makes for a more natural transition from bass-to-mids, it doesn't feel disjointed but better integrated. It's a more speaker-like sound where the sounds combine more before arriving at your ear-drum.
The mids are a bit more recessed and more even. with no spikes and perfect tonality (to my ear and preference).
The highs are more extended and zingy, but above that 9K elevated zone in 598. Can't figure out exactly where. A bit more grainy in the highs, yes but not much.
Overall a warmer and even less fatiguing sound than 598, mainly because of the toned down high-mids and added bass. More fun, but also probably less accuracy.
This are early impressions, I'll have to spend more time with them, for now I like both headphones for various occasions, moods. The 598 is clearly better for games, the 518 at a lower volume is more fun, thumpy, and less fatiguing for long-time at work use.
