Pros: Weighty, firm clamp, massive earcups. Shure sound, replaceable one-sided cable, great build quality. So cheap.
Cons: Weighty, small fit, little design niggles.
After burn-in and listening to them for a hundred hours or so, plus live mix time this is my perspective on their audio.
Coming from Sennheiser HD280 Pros and Shure SE215s, these seem to be amazingly balanced.
They have the incredible Shure warmth and vocal clarity, but still extend their highs extensively. I have always found problem frequencies in all the other headphones I use, like the HD280 Pros have the weird 200Hz lump which is a constant annoying humming espesh during live sessions, biggest turn-off for me. But the SRH840s seem to be perfectly matched to the system I work with. Boominess when there is, sibilance when there is. Simply great monitoring cans for a large-ish system.
And the detail! Basically, if I can hear the string slap in the third minute of Tchaikovsky's Nutcracker Suite and hear pages turning throughout the masterpiece, I am completely satisfied.
The soundstage is OK. It's not amazing and a tad forward at times which you'd least expect, but those incredible highs help spread it out.
The cans do well above average for most genres but there are times you wish you had something more like the Beyerdynamic DT880 Pros or AKG 701's with a lot more air and breath to them simply because they're open, but then again, these ARE meant for professional use, and open cans would be damn annoying when you're trying to PFL/solo anything live with 90dB of background noise.
I seriously have been on the hunt for the best live monitoring headphone and can't find anything better for even double or triple the price.
There is a lot of plastic on this can, but the back of the inner circle driver housing is metal, adding to that definition I mentioned earlier while the outer casing is plastic adding to that Shure warmth. The main headband of the phone is metal based, simply because plastic will never have the same kind of elasticity, but the frame that holds the earcups is pure plastic because of the rigidity required to hold the shape.
I do have to complain about a few things though, mainly design-wise. Most significant is probably due to my big head. When using my HD280 Pros, dropping each side to its maximum length causes only the bottom half of my ears to be covered, but with the SRH840's I have to drop them down the whole way for them to perfectly cover my ears. Now you might ask, "then what's the problem?" As a Sound Engineer I am trained in my thinking to always have a little headroom for everything. Save some for a rainy day, that kind of thing. It's already at its limit and that leads to another problem.
This one would the be smaller cables leading to earcup. Because the side lengths are at maximum, these smaller cables are almost at full stretch and I don't know how good the strain relief is, but if there was ever to be some serious snaggage, it could mean the death of the sound in the right earcup.
These cans are also the heaviest, and the 4m of coiled cable doesn't help either. But it does fold away quite neatly, with the cable detachable. Too bad it doesn't fold flat.