Can't recommend these. If you are looking for lo-fi headphones, these could be classified as upper range of the lo-fi range. They suffer from an annoying metallic, empty character, and I could never settle on a EQ setting that was beneficial for all music. Compared with sub-$100 headphones, these are clearly superior in terms of resolution and dynamics -- and in fact, I still use them sometimes if I'm lying in bed, out in public, etc, as they are pretty compact for full size headphones, and run a good volume off of just about anything. They don't remotely compare to my TH-900 ($1,200) or HE-6 ($1,000), and were a step down from the HD600 ($330) and HE-400S ($300). They are a step above the HD668B ($40).
As lo-fi headphones, sound stage is basically non-existent (and along with it, so is imaging). Dynamics and speed are average. Resolution is upper lo-fi, and just a step below mid-fi headphones like the HD600. Micro-details are absent. Treble extension is decent. Bass is...hold on. I just got this Ragnarok, let me check what a 400VA 100,000 uF amp can do with the K553....okay, definitely better in terms of bass production than I remember them out of my other amps, but a 36 lbs amp can't transform these headphones. Bass is fairly articulate and tight, and puts out good energy, but it just won't extend that low -- and I'm talking about them plugged into a giant amplifier being fed by 4.6v balanced outputs from a large dual power-supply DAC. Your phone will drive these, but it WILL sound anemic in comparison -- please have expectations set correctly. I will say, one of my reference tracks (A Shanty in Old Shanty Town - Cephas and Wiggins) it does a good job with the kick-drum (deep, dark thumps) that is basically indistinguishable from my TH-900. Like ALL headphones, they benefit from a dedicated amp and high quality DAC -- if you are stuck with a certain budget, and need to make room for a good amp and DAC, I will admit that these aren't that bad, especially if you consider their portability.