QUOTE(polkiuj @ Nov 30 2011, 11:18 AM)
Akuma, no offense but if u have never tried both, you are not in a position to compare them. Also if a 601 has not enough power to drive them, I dunno what will. Maybe a speaker amp?? A 601 can even drive a HD650 and if it can't push a 668B the u better not buy a 668B because the amp u need to drive it will cost more than a thousand bucks.
If u think piercing highs, recessed mids and flat bass is the ideal monitoring signature then ok. 668b is ideal.
For me, a monitor should not have a sound preference and ideally flat.
A 440 is nearly there in that it is flat and boring (no musicality or sound preference)The 668B is way too bright to be a monitor. Simply because sounds from speakers should not come out like that. A monitor should be relatively bright but not to the 668b level.
I do not hate highs. I own a re0 which many praise its highs. But if it's super extremely sibilant then it is a serious issue. It is FAR worse than a dba02 which also has relatively piercing highs.
Stop reading reviews as they are pretty much useless. Try the headphones u wanna buy. Test around to see what you like. If u can't, buy something that has a return policy. Worst case scenario, lose some $$ in a buy sell.

Don't worry about that i'm fine. Everyone have a personal taste and may give different opinion. But please try to keep it positive and give it as a second thought. Don't need to flame.
I'm in no position to comment 440 because I did not own one, and I only tested it for a short time. I'm just comparing it to the higher ends headphones with the 668B at the comfort of my home where all distraction are kept at the most minimum.
The power of 601 does not differ much in power as 602 which I use. Amplification or drivability is also another topic which I'm having a hard time to explain just like producing the ideal bass. There are way too many common mistakes about it out there which it is impossible to correct. Using a speaker amp to compare may sound amateurish in the sense that you have used the wrong example. Using a similar range of power headphone amplifier such as high current amp that can drive orthordynamics will be a better example. Nobody is going to use speaker output to drive their low impendance, high sensitivity dynamic headphone, but there are some cases that drive their high impendance and low sensitivity headphone such as HD650. But anyway amplifier have two types just like a headphone. One is current feedback which and another type is voltage feedbacks. We can't generalize this thing based on specs alone because what come out at a paper may not be the same in real world usage. For example, certain low impendance headphone are suppose to be current sensitive but in the end they require more voltage instead. And another headphone having the same ohm ratings may requires more current to push it than requiring more voltage. It is hard to find this specs because most headphone amp are rated in current instead of having both.
Anyway back to the topic again, you can drive the HD650 to certain loudness does not mean you can give it a proper controls on the drivers. This is what i'm touching and not the common mistakes of loudness or volume part. For me all headphones with the exeception of orthodynamics are very easy to drive in the sense that they can get enough volume even out of a headphone output from pc. Does that mean a a pc output can drive it well when they can power them. No, because they do not have the proper controls on the driver of the headphone.
Ok, so in 601/602 case I find it that I can drive the HD668B on high settings with a volume of two or less but having an additional 8 volume of headroom does not mean I can still push it to drive it. Basically you can push the volume up by a large degree but you are not going to improve the proper controls of the drivers. For me the hifiman does not have the ability to creat a proper control to those headphone that are very current sensitive even down to both dynamic and balanced armature IEM or those higher ohm headphone that requires lots of voltage. They just work better in between. (then again I cant generalize it because all headphone reacted differently when they are fed to different headphone)
Using an expensive amp to represents something is also a mistakes with most people in audiophile world. For example I can use a JH16PRO with a Hippo amp (RM260 AAA battery powered version) and get a better sound/ matching than JH16PRO with SPL Auditor. The price differences you count yourselves. The match with the hippo amp is also much better than with the JDSLabs Cmoy which is suppose to have better techinicality than what the hippo amp could produce and in a level that is almost light year ahead. And I have tp emphasize this over and over again because in the end you are listening to music and not your setups.
The highs does pierce abit so getting a warmer amps to tone it down will be better. The mids, yes to many they are recessed, maybe its because my comparison is against DT880 which has much worse than the HD668B and the Shure SE535 that have a bit of problem in its driver limitation. (But the mids really is good in Shure SE535 so I'm putting the Superlux's mid in between) The bass is nowehere flat at all because they are boosted at midbass area. Whatever you are comparing with you at that will give you a different response to your thoughts.
Then again the sound impression you are hearing on 668B might be because of two possible factors. First is the comparison that you are using at the times of doing your reviews. Second, it could also be a sign of your 601 is under power or does not have a good synergy with it just as stated above. Just touching on the bass alone, I find it to be hardest frequency to produce over any other range. It is so hard that it is almost impossible to hear the best bass or the most ideal bass. I'm a bass addict but not those booming type but the high quality type of bass. For me I still haven't found the ideal bass yet.
Yes some monitor engineer do prefer flat frequency over other types. But to me the most ideal type is the one which is neutral because in the end you down want to tone down your frequency when monitoring. Flat frequency headphones tends to artificially tone down the frequency into an ideal flat just like an eq. So in the end I don't really like to compromise my music by toning it into a flat frequency but instead a more musical type.
There are many type of monitor headphone so the ideal sound still have to depends on the person or the tracks that they are producing. For example DT880 also sounded bright but the smoothness of the sound helps it tones down a bit. Some wanted the treble because they want to listen to the details in the song because using a microdetail are harder in design than boosting the treble itselfs. That's why most of the headphone around labeled as detailed cans are hot in their treble especially for mainstream pop song.
Yup that is what a lot of people said about the treble because headphone does not have enough time or space to tone down the treble before it hits our ears. And lots of mainstream pop songs are recorded with trebly sound that's why they are good on speaker but will sounded piercing on headphone use especially something as bright as HD668B. But most of my songs don't really have boosted treble so i'm fine with it.
Sometimes it is very hard to explain on the highs or even other frequency range. We still haven't develope enough vocabulary to fully identify a certain sound. For example just the highs alone (not touching other frequecy range yet) will have many different type and level of refinement. Even when we hear piercing highs. there are still so many type of piercing highs in which some are more smoother, some are more refine, some are a side effect for better details some piercings high are annoying. So basically most of us just generalize the tone into piercing highs and end it that way without truly identifying it. So you might like a certain type of highs but hated others while other people might like the type that you hated. So sound preference plays a role here.
Besides that matching also plays a very important role and so far I find that mathcing is more important than the price range or reading a general impression of the sounds. For example a bright headphone with a bright amp match together might have a different results as in better refine highs if their synergy matches each other. And other headphone put on it may sound ovely bright. So matching is as important as sound preference beauce it is hard to generalize the final outcome of the sound. We can only guess.
Anyway TS, if you can try to contact a few forumer and ask them out for a small TT session to try out the headphone you mention. You might be able to learn a thing or two in the process.
P/S: Sorry, no offence though. I'm just trying to correct some common misunderstanding which I find it to be plaguing the audiophile world and not meant to be against you alone. It is similar in concept to photography where you own an expensive nikon camera or a canon high end series and that means you are a better photographer than an experienced professional who uses low to mid ends camera. That's why I don't like to put what I'm using in my siggy to identify my experience because owning many headphone does not mean he is a good audiophile. I only use them when making comparison and is by no mean of stating my experience level. The best audiophile are those that try to find the best sound in both sound quality and matching sound preference for them within a certain budget level. In other words, poor people might be the best audiophiles because of their budget constrain forcing them to choose the best one. (I'm just making a generalization here) So owning one of the best entry level priced headphone does not mean you are not an audiophile and owning the most expensive headphone does not mean you are an audiophile. It is the search for best music reproduction is the main thing in audiophile world and not represented by the gears they own.