Today I'll give you my impressions on the Headphile creations known as Terminator V4's. Originally they were Beyerdynamic DT770's with 80 ohm impedance. The previous generation of these headphones were known as the Darth Beyers, for the uninitiated.
Terminator V4's: These were one of the Dealpage items that came up over time, so they have Larry's BlackMax cable, and are terminated with a regular 1/4" plug. They also have the regular velour pads. The V4's actually feel a little bit lighter than the regular, unmodded Beyerdynamics DT770s as well. Price? If you order a custom pair off the Headphile site, it's anywhere from $600 on up, typically.
Bass: These have a TON of bass. For the record, I listen to them with the top two holes covered with electrical tape. Larry (the Headphile creator) says that he doesn't think this sounds good for the type of music he listens to. He must listen to rap and/or R&B, because fully unleashed, the bass is monsterous and great for that kind of music. But for metal? It encroaches on the guitars way too much. The bass guitar and kick drum can totally take over a song.
EDIT: That's not to say that the bass notes actually intrude on the mids. No, they stay well separated from the rest of the notes. My opinion is that the bass is in such great quantity, depending on the song, we might hear much more of it than guitar riffing or singing. But what's great about the V4 is that it's so easy to experiment! Little pieces of electrical tape cover the holes well, and if you get decent quality tape, it won't leave any adhesive on the plastic cups. So if you don't like what you've done, just peel that sucker off and let the V4's do their thing.
That said, properly tamed (EDIT: in my opinion), the bass pumps a lot of life into our beloved metal. Let me try a new track here: Metallica's "The Thing That Should Not Be" becomes very dark and evil sounding on these headphones. Bass guitar on down, I now realize just how "one-note" the regular DT770 bass sounds in comparison. Bass is much more musical on the Terminator V4's.
How 'bout the familiar "Dawn Patrol?" Again, the bass guitar is much more present and forceful than I've heard in other headphones. But I'm more impressed with how the bass sounds played along with the guitars, because right after this short track, we get "Rust In Peace...Polaris." The drums start off fast and deep, and the V4's just keep right on pounding when the guitars start up. It makes everything feel energetic and visceral. I wouldn't call the bass fast or tight, because there is some detectable decay. But I wouldn't say that this slows the headphones down any, because...
Speed: ...these things are definitely faster than the stock DT770s. No, the V4's don't resolve the rhythm guitar during the solo of "Mechanix" any better than the regular DT770s, or the Sennheiser HD600s, but Mustaine's shredding is revealed almost as well as with the Sony SA5000's.
So if the rhythm guitar is basically a blur, how can these feel fast, while the HD600's are slow? I believe it has to do with the lack of bass on the HD600's part. With the V4's, I can hear/feel a little bit of the lower register chugging of the rhythm guitar, not to mention the drums. It provides a nice rhythm for Mustaine's solo to ride on. The HD600's are devoid of any chugging or drum pounding on this solo, so all we get is a nicely portrayed solo on some sludge--very flat. With the V4, I'll say we get a nicely portrayed solo on top of sludge, resting on a rocky layer of bass.
Everything Else: At low volumes, the bass will overpower the guitars. No doubt there. But, crank it up a little, and the mids fill out nicely. I find that I have to listen at a slightly higher volume than normal to really balance out the lead and rhythm guitars with the bass. This can be dangerous...
It's well documented that the V4's and Darth Beyers are warm/dark sounding with rolled off treble, especially compared to the stock DT770's. Yes, this is true. You won't hear cymbal crashes as crisply, but I didn't find it to be an issue.
Last point: These V4's are well broken in. Say, over 500 hours. They sound quite a bit more balanced now than when they were brand new. Even so, I give these a nod of approval. I could definitely listen to metal on the Headphile V4's. Despite the crappy recording or production or whatever, I've never heard Metallica's "Ride the Lightning" CD sound so good.