tdockweiler
Headphoneus Supremus
(Scroll down to "TL;DR" review if you don't want to read my long winded impressions)
This entire post is based on 10 hours of comparing both over several days. I loved every minute of it and listened to each song 2-4 times on each headphone. No changes in adaptors, cables, sources or amps occurred. I have 6 pages of listening impression notes and comparisons upon request. I wish I was lying. 13 pages total. Yikes!
HD-598
It's been said before and I'll say it again that this is a "do everything" headphone. It's not terrible for any one single genre, but quite good for all of them. If that wasn't enough, it's one of the best budget headphones there is for gaming and movies. For the people who only need one headphone, this is one of the rare headphones that will be good in every area. The only other headphones that fit this description are the HD-600 and AKG K240 Studio.
I remember when I first listened to the HD-598 I was surprised at how clear sounding it was compared to my old non-silver screened HD-600 I had in the past. The 598 to my ears felt more detailed and much brighter. When I say it's brighter I don't want to give people the wrong impression. It's NOT too bright and is certainly not treble heavy in any way. If there is one word I could use to describe the HD-598's signature, it is "smooth". It's very smooth sounding and no frequency to me sticks out. I can't say the same thing about many other headphones. Maybe the HD-600. As much as I love the HD-600 (silver screen), the HD-598 makes it look like a snore fest.
It has a decent amount of bass and some forward sounding mids and still manages to sound perfectly balanced. There are very few songs where its mids can be bothersome. In fact, up until today there was not one example of where the forward mids became a problem for my ears. They're forward, but not too forward. Nowhere near as forward as the mids on my old ATH-AD2000!
I think treble-heads would not love this headphone. Compared to the K702 and DT-990 it feels like the treble is kind of smoothed over a tad and tamed. Music that is very brightly mastered and harsh sounding will still be that way slightly, but it's tamed just a tad. Not as much as the HD-600 with its stock cable (from what I recall).
I'm a huge fan of some Asian Pop music and for those that love that type of thing, you will love this headphone! It's possibly one of the best headphones there is for female vocals. Utada Hikaru's Japanese music is especially good on this headphone! Her music can be annoying and un-natural sounding on a treble heavy headphone, but not so on this headphone.
One thing I'd also like to point out is that the soundstage of the HD-598 is HUGE compared to that of the modded HD-555 and even the HD-600 and HD-650. I've had all versions, but I haven't tried the HD-650 with any $1000 "magic" amp. I find it impossible to believe that the HD-600 and HD-650's soundstage could be as large as that of the 598 with a specific amp. It sure would be nice. The soundstage of the HD-598 is the 3rd largest I've heard. The AD700 would be 1st and the K702 2nd. Usually when I hear a huge soundstage, sometimes vocals and its mids feel a bit distant, especially with a poor amp. That isn't the case here. You almost always get that up-front experience, but it depends on the recording.
The level of detail is also very high. It's not a super revealing detail monster, but it's detailed enough for me. It actually can even pick up recording hiss quite easily. For comparison it's much harder to spot on my HD-650. I won't go there and mention why I think this is. The HD-598 is still fairly forgiving of source files. You don't need to go and convert all your 320kbps MP3 files to Lossless. I should point out that it's much easier to spot lower quality tracks on the HD-650 with an upgraded (cheap Mogami) cable compared to the HD-598.
The biggest negative of the HD-598 is that for a $175-$250 headphone, the sound clarity is just "good". I think it's a bit wrong to say it has the sound clarity of the HD-650 and K702. It doesn't to me. Not even close. The HD-600 is slightly clearer, but the differences are not super huge. It's stupid to put this into a percentage, but the HD-600 (with stock cable) sounds about maybe 5% more clear. I imagine many people will prefer the HD-600 to the HD-598. I think the HD-598 is easier for more people to like though. Now if only Sennheiser would release a black version! Don't let the color ruin it for you. I disliked the color but it has grown on me. HD-600 is more neutral, but the 598 is still very well balanced.
The main reason I love the HD-598 is just how it makes music so much more fun to listen to. Music just really comes alive on the 598 and it's so much more engaging. It's a near perfect match for most of my favorite genres. It's not as laid back as the HD-600 and HD-650 and its mids are more forward sounding. The HD-600/650 are "technically" better and it all comes down to preferences. I've found that with specific amps and cable, the mids on the HD-650 can sound similar to those of the 598, but not quite. HD-650 is one good headphone (with correct amp), but HD-598 matches my sound preferences. My only hope is that Sennheiser can make another headphone that has the sound signatue of the 598, but is technically better than even the HD-650 and has a clearer sound than the 598! I can't wait to hear what an HD-698 sounds like!
HD-598 really excels with pop music and even rock such as Pearl Jam. It's the perfect headphone for Jpop/Cantopop and especially female vocals. If you like Asian pop music, you NEED the HD-598! I think it's just "good" with acoustic, classical, ambient and bass-light electronic music. I guess for its price, there isn't many other good options for classical under $250 that doesn't need a very powerful amp.
K601
When I got this in and tried it with my new amp I was "Wowed" with its sound. It seemed to have my near perfect sound signature. I had a pair last year also, but I had some bad amp synergy and sold it. The K601 has perfect synergy with even a cheap amp like the $120 E9. It actually sounds better on the E9 than my K702 does! With this headphone, amp synergy is more important than the price of the amp itself. My Asgard hated this headphone and that's a good amp. At first I got the impression that the K601 was like a more energetic and slightly more aggressive HD-598. This is only partially true. The sound of the K601 is quite well balanced, but nowhere near as smooth sounding and "just right" like the HD-598 is. On day one I felt that the K601 was on a whole other level compared to the K601, but this is also not exactly correct.
The K601 to me is less forgiving of a source file. If it has harsh treble and sounds bad, it's going to sound bad on the K601 no matter what. If you take off the K702 and immediately put on the k601 you'd be saying "Where'd the treble go?". The K601 has more than enough treble to me, but nowhere near as much as the K702. It still has way more than the HD-598. The HD-598 tends to smooth over some very bright songs (slightly) but the K601 does not to my ears. Maybe compared to the K702. Compared to the K702, the K601 just feels more natural sounding to my ears, especially with vocals. I hope I can tame the treble of my K702 eventually.
The mids of the K601 to me are slightly forward (sounding), but not as much as that of the HD-598. Today I was listening to an Eddie Vedder song called "Rise" and it was un-listenable on the 598 due to the forward mids. On the K601 it was perfect. I should point out that this was the first song since owning the HD-598 that I had this problem. Very strange. For 95% of your music, the forward sounding mids of the 598 will not be a problem. I can almost guarantee this. Many people don't know the difference between the K601 and K702 and many incorrectly think they're nearly the same or should sound alike. They don't. I won't go into it much, but imagine the K702 with a more upfront sound with less treble and a much less fatiguing signature. Add in some forward sounding mids and a smaller soundstage and you have the K601. To me the K702 is again "technically" better, but for me the K601 is more natural sounding. The K601 fixes many of the things that people dislike about the K702! It's also a litle more comfortable.
The K601 just doesn't have the clarity and detail of the K702 but its pretty close! Strangely enough I've found the K601 to be like a mix of a more laid back headphone (HD-600) and one with a more aggressive signature. For those that find the HD-600 (with stock cable) too laid back (or boring) the K601 is just the ticket.
I almost forgot to mention it, but if you love a lot of bass, avoid the K601! I like a decent amount of bass, but very rarely like any bass heavy headphones. My main focus is on the mids. I have no problems with the bass on the K601, but I do feel that for some genres, the lack of bass ruins the experience. I'm not going to say I wish they had a little more bass since it's enough for me and I never found myself complaining about a lack of bass. None of my favorite music requires a lot of bass.
What makes the HD-598 better than the K601?
The HD-598 is far better for female vocals (IMO), has a larger soundstage and adds more weight to some instruments and often they seem more natural. At times the K601 can have thin sounding vocals, but it's not too bad at all. The HD-598 generally has a more up-front sound compared to the K601. The K601 still does, but feels slightly further away. The K601 still has forward sounding vocals for sure and the difference between the forwardness of the mids is very, very minor. The sound of the K601 is also a little more airy. I do think the K601 is more true to the recording somehow.
The forwardness of the mids sometimes gives me the false impression of more detail, but the level of detail is so close. The K601 has the slight advantage here with some music.
The HD-598 also has slightly more bass than the K601. Drums are noticeably better on the HD-598. The HD-598 is better for more genres perhaps. No genre that I've tried is terrible. At first I couldn't believe the HD-598 felt like it had more bass than the K601!
What makes the K601 better than the HD-598?
The biggest difference for me was the level of clarity between the two. The K601 has the 598 beat and often it's hard to tell the difference and depends on the recording. Sometimes it's easy to spot and other times not so much. On very simple acoustic, classical or ambient music it's super easy to spot. For these genres, the HD-598 just can't match the clarity and detail of the K601. On very complex songs, the sound clarity of the HD-598 is not so good and can sound congested.
Despite the HD-598 being better for female vocals, on some high quality recordings the K601 makes female vocals sound more crystal clear. That's the best way I can describe them. If you want to tell the difference in sound clarity easily, fire up a game and compare the sounds of footsteps and environmental effects like water, snow, sand, wind etc. On the HD-598 it feels as if there is a sheet of super thin (like Kleenex!) paper over the driver. Still very clear, but not like the K601. I was going to say muffled but it's not THAT bad. Nowhere near that. I don't want people to think that if they get the HD-598 it won't be clear sounding. It is! The only time it bothers me is during specific music and during gaming and I have to be REALLY looking for it. The K601 and K702 have me spoiled when I use them for games.
Despite the huge soundstage of the HD-598, where the K601 really shines is in its imaging, instrument separation and how accurate its soundstage is. I felt the HD-598 had some great imaging, but the K601 has pinpoint accuracy. For gaming, it even has better imaging than the K702!
In specific songs I would hear groups of instruments or sounds on the left and right. On the HD-598 it often felt like the sound was just coming from two blobs. On the K601 it feels as if there is more air or space between all the sounds on each side and you can pinpoint all of them. For example on the HD-598 it felt like there was a piano on the FAR right, but on the K601 is was on the right, but slightly behind my ear. On the K601 I often felt as if sounds were coming from outside my headphone and on the HD-598 it was less noticeable.
When I have sounds going from the left to right and all around, it's much harder to spot them on the HD-598. One example is "Rival" from Pearl Jam. It starts out with a dog growling and moving all around me. It's super easy to spot where it's coming form. On the HD-598 it's much harder. I've noticed this a lot in other music as well.
Classical and especially Acoustic music generally tends to be far better on the K601. Listen to the CD "Talking Timbuktu" with Ry Cooder and Ali Farka Toure and you'll know what I mean. On the HD-598 some of the songs are not clear at all and feel a bit congested. The best I've heard this album was on the ATH-AD2000. I often use "Lasidan" as a test track. Not my favorite genre in the world, but my headphones sure love that CD! I have no clue why, but this music sounds better to me on a thinner sounding headphone. Strange huh?
Acoustic music is often the music that makes the HD-598 look bad. Again, it depends on the album, song and instrument. Shamisen music sounds better on the HD-598 somehow.
Which headphone should I get?
If you listen to a lot of soundtracks, electronic (non-bass heavy), ambient, acoustic and classical music and it makes up a huge percentage of your music listening, the K601 is a no brainer. It's that good. The HD-598 is a much safer option and is easier to like and is better for more genres.
My favorite musicians are from Japan and Jpop sounds good on both. If I had to pick between the two I just could not do it. Some genres I prefer on the K601 and others sound best on the HD-598. I guess I'd pick the HD-598 because of how well it matches up with my music, but again I couldn't keep just one. K601 is technically better. I do think people who like the HD-598 should like the K601. K601 definitely needs a desktop amp. E9 works very well.
TL;DR EDITION
Bass quantity:
HD-598 > K601
Sound Clarity:
K601 > HD-598 (no contest here)
Size of Soundstage:
HD-598 > K601 (this was actually harder than I thought. On one song the K601's Soundstage was massive compared to the 598! I might be wrong here...)
Level of Detail:
K601 > HD-598 (K601 has a slight edge)
Instrument Separation:
K601 > HD-598
Accuracy of Soundstage:
K601 > HD-598
Forwardness of mids (Yes, this is important to me):
HD-598 > K601 (at first it was kind of hard to tell)
Imaging:
K601 > HD-598 (no contest..at all)
Vocal quality (male/female):
HD-598 > K601 (K601 is still very good too and one of the best)
Build Quality:
K601 > HD-598 (easily)
Comfort:
K601 > HD-598 (different for everyone though)
Value:
HD-598 (8/10 at $175-$200)
K601 (10/10 at $190. I'd pay up to $300, seriously. Not worth any more)
Treble Quantity:
K601 > HD-598 (easily)
Musicality:
HD-598 > K601 (K601 sure isn't very far behind at all!)
Sound quality of the didgeridoo:
HD-598 > K601
Gaming:
K601 > HD-598 (HD-598 is not far behind and much easier to drive)
Movies:
Depends on genre. I usually prefer the K601. HD-598 is very good for movies, but I prefer the HD-600 by far. Strangely I hate my HD-650 for movies!
Listening Fatigue (less to more):
HD-598 > K601 (both are non-fatiguing to me)
This entire post is based on 10 hours of comparing both over several days. I loved every minute of it and listened to each song 2-4 times on each headphone. No changes in adaptors, cables, sources or amps occurred. I have 6 pages of listening impression notes and comparisons upon request. I wish I was lying. 13 pages total. Yikes!
HD-598
It's been said before and I'll say it again that this is a "do everything" headphone. It's not terrible for any one single genre, but quite good for all of them. If that wasn't enough, it's one of the best budget headphones there is for gaming and movies. For the people who only need one headphone, this is one of the rare headphones that will be good in every area. The only other headphones that fit this description are the HD-600 and AKG K240 Studio.
I remember when I first listened to the HD-598 I was surprised at how clear sounding it was compared to my old non-silver screened HD-600 I had in the past. The 598 to my ears felt more detailed and much brighter. When I say it's brighter I don't want to give people the wrong impression. It's NOT too bright and is certainly not treble heavy in any way. If there is one word I could use to describe the HD-598's signature, it is "smooth". It's very smooth sounding and no frequency to me sticks out. I can't say the same thing about many other headphones. Maybe the HD-600. As much as I love the HD-600 (silver screen), the HD-598 makes it look like a snore fest.
It has a decent amount of bass and some forward sounding mids and still manages to sound perfectly balanced. There are very few songs where its mids can be bothersome. In fact, up until today there was not one example of where the forward mids became a problem for my ears. They're forward, but not too forward. Nowhere near as forward as the mids on my old ATH-AD2000!
I think treble-heads would not love this headphone. Compared to the K702 and DT-990 it feels like the treble is kind of smoothed over a tad and tamed. Music that is very brightly mastered and harsh sounding will still be that way slightly, but it's tamed just a tad. Not as much as the HD-600 with its stock cable (from what I recall).
I'm a huge fan of some Asian Pop music and for those that love that type of thing, you will love this headphone! It's possibly one of the best headphones there is for female vocals. Utada Hikaru's Japanese music is especially good on this headphone! Her music can be annoying and un-natural sounding on a treble heavy headphone, but not so on this headphone.
One thing I'd also like to point out is that the soundstage of the HD-598 is HUGE compared to that of the modded HD-555 and even the HD-600 and HD-650. I've had all versions, but I haven't tried the HD-650 with any $1000 "magic" amp. I find it impossible to believe that the HD-600 and HD-650's soundstage could be as large as that of the 598 with a specific amp. It sure would be nice. The soundstage of the HD-598 is the 3rd largest I've heard. The AD700 would be 1st and the K702 2nd. Usually when I hear a huge soundstage, sometimes vocals and its mids feel a bit distant, especially with a poor amp. That isn't the case here. You almost always get that up-front experience, but it depends on the recording.
The level of detail is also very high. It's not a super revealing detail monster, but it's detailed enough for me. It actually can even pick up recording hiss quite easily. For comparison it's much harder to spot on my HD-650. I won't go there and mention why I think this is. The HD-598 is still fairly forgiving of source files. You don't need to go and convert all your 320kbps MP3 files to Lossless. I should point out that it's much easier to spot lower quality tracks on the HD-650 with an upgraded (cheap Mogami) cable compared to the HD-598.
The biggest negative of the HD-598 is that for a $175-$250 headphone, the sound clarity is just "good". I think it's a bit wrong to say it has the sound clarity of the HD-650 and K702. It doesn't to me. Not even close. The HD-600 is slightly clearer, but the differences are not super huge. It's stupid to put this into a percentage, but the HD-600 (with stock cable) sounds about maybe 5% more clear. I imagine many people will prefer the HD-600 to the HD-598. I think the HD-598 is easier for more people to like though. Now if only Sennheiser would release a black version! Don't let the color ruin it for you. I disliked the color but it has grown on me. HD-600 is more neutral, but the 598 is still very well balanced.
The main reason I love the HD-598 is just how it makes music so much more fun to listen to. Music just really comes alive on the 598 and it's so much more engaging. It's a near perfect match for most of my favorite genres. It's not as laid back as the HD-600 and HD-650 and its mids are more forward sounding. The HD-600/650 are "technically" better and it all comes down to preferences. I've found that with specific amps and cable, the mids on the HD-650 can sound similar to those of the 598, but not quite. HD-650 is one good headphone (with correct amp), but HD-598 matches my sound preferences. My only hope is that Sennheiser can make another headphone that has the sound signatue of the 598, but is technically better than even the HD-650 and has a clearer sound than the 598! I can't wait to hear what an HD-698 sounds like!
HD-598 really excels with pop music and even rock such as Pearl Jam. It's the perfect headphone for Jpop/Cantopop and especially female vocals. If you like Asian pop music, you NEED the HD-598! I think it's just "good" with acoustic, classical, ambient and bass-light electronic music. I guess for its price, there isn't many other good options for classical under $250 that doesn't need a very powerful amp.
K601
When I got this in and tried it with my new amp I was "Wowed" with its sound. It seemed to have my near perfect sound signature. I had a pair last year also, but I had some bad amp synergy and sold it. The K601 has perfect synergy with even a cheap amp like the $120 E9. It actually sounds better on the E9 than my K702 does! With this headphone, amp synergy is more important than the price of the amp itself. My Asgard hated this headphone and that's a good amp. At first I got the impression that the K601 was like a more energetic and slightly more aggressive HD-598. This is only partially true. The sound of the K601 is quite well balanced, but nowhere near as smooth sounding and "just right" like the HD-598 is. On day one I felt that the K601 was on a whole other level compared to the K601, but this is also not exactly correct.
The K601 to me is less forgiving of a source file. If it has harsh treble and sounds bad, it's going to sound bad on the K601 no matter what. If you take off the K702 and immediately put on the k601 you'd be saying "Where'd the treble go?". The K601 has more than enough treble to me, but nowhere near as much as the K702. It still has way more than the HD-598. The HD-598 tends to smooth over some very bright songs (slightly) but the K601 does not to my ears. Maybe compared to the K702. Compared to the K702, the K601 just feels more natural sounding to my ears, especially with vocals. I hope I can tame the treble of my K702 eventually.
The mids of the K601 to me are slightly forward (sounding), but not as much as that of the HD-598. Today I was listening to an Eddie Vedder song called "Rise" and it was un-listenable on the 598 due to the forward mids. On the K601 it was perfect. I should point out that this was the first song since owning the HD-598 that I had this problem. Very strange. For 95% of your music, the forward sounding mids of the 598 will not be a problem. I can almost guarantee this. Many people don't know the difference between the K601 and K702 and many incorrectly think they're nearly the same or should sound alike. They don't. I won't go into it much, but imagine the K702 with a more upfront sound with less treble and a much less fatiguing signature. Add in some forward sounding mids and a smaller soundstage and you have the K601. To me the K702 is again "technically" better, but for me the K601 is more natural sounding. The K601 fixes many of the things that people dislike about the K702! It's also a litle more comfortable.
The K601 just doesn't have the clarity and detail of the K702 but its pretty close! Strangely enough I've found the K601 to be like a mix of a more laid back headphone (HD-600) and one with a more aggressive signature. For those that find the HD-600 (with stock cable) too laid back (or boring) the K601 is just the ticket.
I almost forgot to mention it, but if you love a lot of bass, avoid the K601! I like a decent amount of bass, but very rarely like any bass heavy headphones. My main focus is on the mids. I have no problems with the bass on the K601, but I do feel that for some genres, the lack of bass ruins the experience. I'm not going to say I wish they had a little more bass since it's enough for me and I never found myself complaining about a lack of bass. None of my favorite music requires a lot of bass.
What makes the HD-598 better than the K601?
The HD-598 is far better for female vocals (IMO), has a larger soundstage and adds more weight to some instruments and often they seem more natural. At times the K601 can have thin sounding vocals, but it's not too bad at all. The HD-598 generally has a more up-front sound compared to the K601. The K601 still does, but feels slightly further away. The K601 still has forward sounding vocals for sure and the difference between the forwardness of the mids is very, very minor. The sound of the K601 is also a little more airy. I do think the K601 is more true to the recording somehow.
The forwardness of the mids sometimes gives me the false impression of more detail, but the level of detail is so close. The K601 has the slight advantage here with some music.
The HD-598 also has slightly more bass than the K601. Drums are noticeably better on the HD-598. The HD-598 is better for more genres perhaps. No genre that I've tried is terrible. At first I couldn't believe the HD-598 felt like it had more bass than the K601!
What makes the K601 better than the HD-598?
The biggest difference for me was the level of clarity between the two. The K601 has the 598 beat and often it's hard to tell the difference and depends on the recording. Sometimes it's easy to spot and other times not so much. On very simple acoustic, classical or ambient music it's super easy to spot. For these genres, the HD-598 just can't match the clarity and detail of the K601. On very complex songs, the sound clarity of the HD-598 is not so good and can sound congested.
Despite the HD-598 being better for female vocals, on some high quality recordings the K601 makes female vocals sound more crystal clear. That's the best way I can describe them. If you want to tell the difference in sound clarity easily, fire up a game and compare the sounds of footsteps and environmental effects like water, snow, sand, wind etc. On the HD-598 it feels as if there is a sheet of super thin (like Kleenex!) paper over the driver. Still very clear, but not like the K601. I was going to say muffled but it's not THAT bad. Nowhere near that. I don't want people to think that if they get the HD-598 it won't be clear sounding. It is! The only time it bothers me is during specific music and during gaming and I have to be REALLY looking for it. The K601 and K702 have me spoiled when I use them for games.
Despite the huge soundstage of the HD-598, where the K601 really shines is in its imaging, instrument separation and how accurate its soundstage is. I felt the HD-598 had some great imaging, but the K601 has pinpoint accuracy. For gaming, it even has better imaging than the K702!
In specific songs I would hear groups of instruments or sounds on the left and right. On the HD-598 it often felt like the sound was just coming from two blobs. On the K601 it feels as if there is more air or space between all the sounds on each side and you can pinpoint all of them. For example on the HD-598 it felt like there was a piano on the FAR right, but on the K601 is was on the right, but slightly behind my ear. On the K601 I often felt as if sounds were coming from outside my headphone and on the HD-598 it was less noticeable.
When I have sounds going from the left to right and all around, it's much harder to spot them on the HD-598. One example is "Rival" from Pearl Jam. It starts out with a dog growling and moving all around me. It's super easy to spot where it's coming form. On the HD-598 it's much harder. I've noticed this a lot in other music as well.
Classical and especially Acoustic music generally tends to be far better on the K601. Listen to the CD "Talking Timbuktu" with Ry Cooder and Ali Farka Toure and you'll know what I mean. On the HD-598 some of the songs are not clear at all and feel a bit congested. The best I've heard this album was on the ATH-AD2000. I often use "Lasidan" as a test track. Not my favorite genre in the world, but my headphones sure love that CD! I have no clue why, but this music sounds better to me on a thinner sounding headphone. Strange huh?
Acoustic music is often the music that makes the HD-598 look bad. Again, it depends on the album, song and instrument. Shamisen music sounds better on the HD-598 somehow.
Which headphone should I get?
If you listen to a lot of soundtracks, electronic (non-bass heavy), ambient, acoustic and classical music and it makes up a huge percentage of your music listening, the K601 is a no brainer. It's that good. The HD-598 is a much safer option and is easier to like and is better for more genres.
My favorite musicians are from Japan and Jpop sounds good on both. If I had to pick between the two I just could not do it. Some genres I prefer on the K601 and others sound best on the HD-598. I guess I'd pick the HD-598 because of how well it matches up with my music, but again I couldn't keep just one. K601 is technically better. I do think people who like the HD-598 should like the K601. K601 definitely needs a desktop amp. E9 works very well.
TL;DR EDITION
Bass quantity:
HD-598 > K601
Sound Clarity:
K601 > HD-598 (no contest here)
Size of Soundstage:
HD-598 > K601 (this was actually harder than I thought. On one song the K601's Soundstage was massive compared to the 598! I might be wrong here...)
Level of Detail:
K601 > HD-598 (K601 has a slight edge)
Instrument Separation:
K601 > HD-598
Accuracy of Soundstage:
K601 > HD-598
Forwardness of mids (Yes, this is important to me):
HD-598 > K601 (at first it was kind of hard to tell)
Imaging:
K601 > HD-598 (no contest..at all)
Vocal quality (male/female):
HD-598 > K601 (K601 is still very good too and one of the best)
Build Quality:
K601 > HD-598 (easily)
Comfort:
K601 > HD-598 (different for everyone though)
Value:
HD-598 (8/10 at $175-$200)
K601 (10/10 at $190. I'd pay up to $300, seriously. Not worth any more)
Treble Quantity:
K601 > HD-598 (easily)
Musicality:
HD-598 > K601 (K601 sure isn't very far behind at all!)
Sound quality of the didgeridoo:
HD-598 > K601
Gaming:
K601 > HD-598 (HD-598 is not far behind and much easier to drive)
Movies:
Depends on genre. I usually prefer the K601. HD-598 is very good for movies, but I prefer the HD-600 by far. Strangely I hate my HD-650 for movies!
Listening Fatigue (less to more):
HD-598 > K601 (both are non-fatiguing to me)