This is my second pair of EPH-100s. I purchased my first pair in the beginning of 2012 some while after they became a FOTM here on Head-fi. Strangely enough I would have thought that they would have increased in price with the popularity these have, but I got the second pair for $15 less than the first pair I bought. The first pair survived a lot of hours of music at work, but the housings were starting to fall apart. The tips have also become very uncomfortable and I thought it was about overdue to get a second pair. 
 
Listening to the replacement set I was immediately smitten with these all over again. What a bargain for the sound quality on offer! I can't think of any headphone that I've listened to that offers even remotely close to the amount of bang for the buck that these do. In some ways I like them more than the Westone 4s I had previously. The W4s are obviously more detailed and neutral, but these have a certain fun factor and they sound great with modern music and anything electronic. The dynamic drivers also convey a lot of impact which contributes to the fun factor of bass heavy music.
 
Pros:
Excellent sound quality, great bass, very good separation and imaging in the mid range, smooth sounding, very good isolation. I was wearing these while sitting close to a couple of 5-axis CNC routers and these isolated the noise very well.
 
Cons:
The housings on my first pair fell apart after a year and half's usage. Difficult to get the tips off if you wish to swap them. the ear tips become uncomfortable with extended listening. They also seem to lose some of their flex as they become older. Treble is a bit non descript, but adequate.

I got the Project Sunrise ii amp specifically to drive my Hifiman HE-500s. I was interested in buying the kit, but doing a trade-off with the cost involved in getting a proper soldering iron I decided to buy the pre-assembled kit in stead. I have to give kudos to Garage 1217 (Jeremy) as the amp was excellently packaged. They take great care to make sure your amplifier arrives in perfect condition. The amp build quality and soldering work is superbly done.
 
I was immediately impressed with the power this amplifier put out with the HE-500s. In the past I have used a Lehmann Black Cube Linear and my Audiolab M-DAC headphone output to drive the HE-500s and whilst it didn't sound particularly underpowered I could immediately notice the difference with the PSii having more headroom and volume to drive the HE-500s to their full potential. The sound is definitely fuller and more authoritative. Putting the volume knob at 10 o'clock is enough to reach loud levels. The Lehmann BCL had to be set to at least 12 o'clock to get decent output and the Audiolab M-DAC to the top half/quarter of its headphone output range. Both solid state amplifiers sounded quite bright and the PSii definitely sounds smoother from top to bottom on the frequency range. The amp has good PRAT with the HE-500 and excellent sound staging, though a lot of this depends on the tube used.
 
I have also done some tube rolling which has been a lot of fun on the PSii as it makes it a breeze to swap out tubes. The stock tube is definitely not bad, but there is definite added mileage to be had with some quality tubes. The biasing process is a bit of pain, though the tweaking is in a convenient location, and I think the auto-biasing feature in the Project Ember amplifier will be very handy. I have since stuck with a 12V ECC801 Zaerix valve which I am enjoying a lot. It is definitely evident that the money saved on the chassis went into producing the best sound quality for the price.
 
Only real negatives that I can think of is that I cannot use my Westone 4 IEMs with this amp as it hisses quite loudly even with the volume set way down. I have detected no hiss with the HE-500. The other negative is that the amp gets very hot even with the open chassis. With the power button and cables at the back you have to be careful not to touch the heatsinks. The amp also picks up interference at times from my cellphone which can also be a nuisance.
 
I'm definitely keeping this amplifier with the HE-500, though I am tempted to get the Project Ember amplifier as well to see what it is capable of. As a bonus the RCA outputs on the PSii also works really well with the B&W MM-1 desktop speakers I have. I'm getting surprisingly good sound out of these little speakers using the line-in.
 
For the price this is a great headphone amplifier and well worth trying out!
 
Other equipment:
Apple Macbook Air 13" 2012
Audirvana Plus
Audioqest Dragonfly
B&W MM-1 desktop speakers

My HE-500 review
Source: Audiolab M-DAC (USB output). First impressions based on Asus Essence STX.
Headphone Amp: Lehmann Audio Black Cube Linear
 

 

 
On first listening to the HE-500 I found a lot that reminded me of the Sennheiser HD580 which I still regard as my reference in terms of what a neutral headphone should sound like. On first listen to the HE-500 you will immediately notice the exceptionally clean and clear sound you get with an orthodynamic transducer which Hifiman are masters of. Switching between the HD580 and HE-500, the HD580 (which I thought up till then to be pretty good in the clarity stakes) to be much grainier by comparison, especially in the treble regions.
 
Bass: (Excellent)
The HE-500 has excellent bass in my view with nice slam and impact. Visceral would be an apt description and it is particularly good at picking out bass notes. This is particularly enjoyable with rock and metal music with bass guitars and also gives orchestral music some body and scale which I found lacking with my dynamic headphones. I really enjoyed going through all my old rock/alternative albums again and found myself listening to albums I haven't listened to in years totally enjoying how different they sounded. There is no boominess and flabbiness to the bass and doesn't dominate the treble or midrange like a lot of other headphones would.
 
Mid-Range: (Excellent)
The mid-range on the HE-500 is musical, nicely detailed and involving, but not forward in your face like a Grado headphone would be. It is slightly more forward compared to the HD580, but does not detract from the overall balance. Violins and piano sound really great and the tonality seems pretty good. With rock music I managed to pick out quite a few extra instruments in songs I thought I knew pretty much inside out. It trashes out tons of detail on guitars. The HE-500 is fantastic with female vocals. The mid-range on this headphone is really excellent and in my opinion its stand out feature.
 
Treble: (Good)
The treble has a slight bit of air to it which most likely has got to do with the sizeable drivers and ear cups.The treble is very clean. I can't really comment on extension as my hearing isn't particularly great in the upper treble regions. The headphone changed quite significantly in the treble during the burn-in period, from being a bit hot to noticeably more mellow after about 50 - 100 hours of burn in. It does have a slight peak around the 10kHz region which seem to give the treble a bit of sparkle which I quite like. The treble is nicely balanced with the rest of the audio spectrum and while not perfect, definitely nothing there to put anyone off.
 
Sound staging and Imaging: (Good)
The HE-500 projects a nicely detailed soundstage, but does lack that last ounce of information. In my view this makes this headphone slightly more suited to rock/pop type music than to large classical works. Imaging is also decent, but not as good as my Grado RS1i's. So whilst I reckon that there are other headphones out there that excel in either of these categories the HE-500 makes up for this by not having any notable weaknesses in either of these categories and by virtue of its excellent sound quality. This also makes the HE-500 a good contender for a wide variety of music.

- Comfort. (Good)
In the beginning the headphone had quite a bit of clamping force. This appears to have reduced somewhat after owning this headphone for some period now. It is a very heavy headphone and you do need to take a break once in a while to give my neck a breather. My neck appears to have gotten used to weight of the headphone after about 6 months. I can now wear the headphone for quite long periods of time without any obvious discomfort. The headband has more than enough padding and the headband pressure is spread out nicely by using memory foam. I prefer the velour pads over the leather pads, though the leather pads are more comfortable in my view. The velour pads add a bit more sparkle to the sound. Hifiman appear to aim this headphone at people with normal to large size heads. I wear the HE-500 on their smallest setting. On the HD580 I have the headband set to 4 clicks down for comparative purposes.
 
- Noise isolation. (Poor)
Leak monster. My wife has complained about the HE-500 quite often and I would put it down as a negative. Not a good option for late night listening in a bedroom. If you have your own listening studio then this isn't a problem. Your listening environment also needs to be pretty well isolated as the HE-500 also lets in a lot of sound from external sources of noise.
 
- Amplication. (Average)
Very dependent on good amplification and matching. With my desktop amplifier the sound is noticeably full and with lots of impact. When under driven the dynamics and bass are lacklustre. I haven't managed to properly power these from a notebook, portable player, AVR or portable headphone amplifier. I will eventually look at upgrading to a more powerful amplifier as I think there are still gains to be made over the Lehmann Black Cube Linear that I'm currently using. The HE-500 also scales nicely with better DACs. I recently upgraded to the Audiolab M-DAC and this provided a noticeable step of improvement in sound staging, detail retrieval and clarity over the Asus Essence STX I used initially for this review.
 
- Construction. (Average)
The headphone itself looks to be solidly constructed and the headband is nice and comfortable. I'm a bit nervous about the assembly mechanism that attaches the ear cups to the headband, but so far no problems. I received the twisted copper cable with my headphone which I think was shipped with the second batch of HE-500 before Hifiman switched over to the silver cable and I quite like the sound, but construction does come across as flimsy and I suspect that the connector or wire might break one day. At least there are a lot of 3rd party cable options out there as well as replacements available from Hifiman. I also received the old velour pads with my headphone which use a flimsy method of attaching to the ear cups. The new attachment mechanism as on my leather pads are a big improvement.
 
- Summary: (Excellent)
I really enjoyed these headphones with all kinds of music, from rock to classic rock, metal, jazz, country and classical music. All in all a superb set of headphones and a terrific all-rounder. After owning this headphone for about 9 months now I find that my other headphones seldom get any listening time. In light of this I reckon the HE-500 is an excellent candidate for people who want to own one single high end headphone that does pretty much everything well. I am hoping to still have the opportunity to listen other high end headphones in order to place the HE-500 in better perspective, but to my ears this is a really fantastic bit of kit will hopefully give me years of listening pleasure.

Great portable amp for those on a budget. Amp arrived packaged really well and was shipped incredibly quickly to my country. Looking inside the tin, the circuit board and components appears to be constructed to high standards, though the front panel connectors on mine weren't aligned 100% but that is nitpicking.
 
I use the headphone amplifier with my Samsung Galaxy S at work and it drives my Sennheiser HD580s very nicely indeed! This little CMoy has good soundstage and bass on the default setting and a clean transparent sound. Highly recommended! The bass boost setting however does distort the sound a bit and muddies up the sound somewhat so I seldom use it. The unit also has a tendency to pick up interference from radios and other RF sources. I hope that newer versions might benefit from better shielding to prevent this.
 
I'm a bit scared that I might damage the casing one day as it looks pretty fragile. To prevent the casing from picking up scratches, I'm carrying the amp in a small sock that I once bought to protect an old ipod with which seems to do the trick. Batteries last surprisingly long, but they are expensive!

A lovely refined headphone in the shape of the Grado house sound. Lovely mahogany earcups add fantastic warmth and detail to stringed instruments. The RS1i give you a lot of insight into hidden details into your music and will get you toe tapping. The RS1is have really opened my world into headphone listening like no other headphone.
 
For the price of these I would expect the build quality to be higher. You have to handle these with care. The metallic gimbal is nice and sturdy compared to Grado headphones lower in the range. Whilst the RS1is do sound fantastic and are hand built, I think these would be more popular at a lower price point. I suspect that I'm quite lucky with my ears as these fit me quite comfortably and they are also very light which helps but I do hear a lot of negative comments out there wrt comfort.

I mainly bought these headphones for use at work and home use since I was looking for a closed headphone that provided a decent bit of isolation, wasn't too expensive (in my country) and somewhat portable. The HD448 appeared to fit that description quite nicely. 
 
I ended up suitably impressed by the sound quality of these as they sound very balanced and the sound only improves once they are burned in (+-30 hours). These headphones have fantastic mids and bring out a lot of detail without being overly warm. They work quite well with instrumental and classical music even with the slightly limited sound stage. I also really like them for jazz and guitar based music. The treble is quite airy and nicely detailed and not overly bright and free from listening fatigue. On some tracks a bit of graininess can become apparent in the treble (much like the HD595). The bass unamped, is a bit flabby and lack definition e.g. difficult to pick out bass notes. The bass is definitely present, but the weakest quality of this headphone. There better closed headphones out there for electronic and bass music. These headphones also aren't very forgiving of poor quality source material.
 
Surprisingly the HD448s ended up being more difficult to drive than I thought they would given their reasonable 32ohm impedance. My Thinkpad workstation had difficulty getting sufficient volume out of the HD448 and only with the Voodoo sound driver could I get good volume on my Samsung Galaxy S. I eventually paired these with a JDS Labs Cmoy headphone amplifier that improved the sound more than what I would have expected. The bass tightened up and the separation improved nicely. It is definitely worthwhile investing in a portable amplifier for these.
 
I personally quite like the design of the headphone, though the size of earcups could have been a touch more accommodating. I don't have overly big ears, but the top part of my ears do get squeezed a bit and start to feel uncomfortable after an hour of wearing these headphones and have to take them off soon thereafter to give my ears a breather. They do, however, feel very light on the head and hardly noticeable. I am not too fond of the plasticky build, but they do look to be moderately durable. Only time will tell (my HD595 suffered from cracks in the headband, but haven't noticed any on the HD448 so far).
 
I would recommend these cans to anybody looking for a balanced sounding set of closed cans for not too much money.