A criminally overlooked option for semi-portable, closed back neutrality
Pros: Neutral balance, detailed, nice texture overall, nice tight, punchy bass, well extended treble for a closed set, good imaging, commendably transparent
Cons: Uncomfortable without slight modification, underwhelming bass extension, can seem somewhat bright, only average soundstage, isolation not stellar
Introduction
Like my DT880, and for almost as long, the SRH440 has been a trusty companion, in its case pulling double duty as my portable headphone and as my "plug-it-in-real-quick" set. Therefore it's only fair it gets a proper review as well.
Back in 2009, Shure released a new line of closed-back, full-sized headphones, which included the SRH240, SRH440, and SRH840. The latter two received a lot of interest, though the flagship (at the time) got the lion's share of that. Essentially, Shure had managed to achieve the impossible, which was to make a closed back headphone that actually sounded good and whose name didn't contain the letter M or the number 5. And some of us who've owned both might say we should drop that qualifier entirely. 
It's funny how people forgot about that once all the shiny new headphones started coming out, though, and the SRH440 especially seems to be entirely abandoned. I'm here to try and turn the tide back in favor of this headphone because I think it's criminally underrated. Is it a giant killer? Probably not, as it's not even better than my humble DT880, but it's a damn good set of headphones for less than $100 these days.
Overall Summary
As usual, here's the shortened version: the SRH440 is a neutral headphone, leaning slightly toward brightness, with an average-sized soundstage, good imaging, punchy but not terribly extended bass, well-textured and balanced mids, and slightly leading treble with good extension for a closed design. It's not particularly comfortable stock, unfortunately, but can be slightly modified (see the relevant section) to improve comfort considerably. Also, do not replace its pads with the SRH840 ones as is commonly suggested, at least until after you've read my special section about that.
What's in the box, Build, Comfort, Ergo, etc.
The box doesn't come with a whole lot in it apart from the headphones, but that's not a big deal. You get the SRH440 itself, a 1/4" adapter, a quick guide/specifications book, a black pleather carrying pouch, and an orange warranty card. The cable also comes separate in the box (if I remember correctly)--yes, if you didn't already know, all the SRHx40 models apart from the SRH240 have a detachable cable. It's coiled, though a straight cable is available from Shure (for $20, last time I checked).
One place where the SRH440 doesn't impress me so much is in the build quality. The structure creaks a fair bit, and the plastics, while they've held up fine for almost two years of fairly constant abuse, feel a bit on the cheap side. The structure also feels a bit hollow, and in some places firm pressure can actually flex some of the plastic pieces. On the other hand, it lacks the utterly asinine hinge system of the old Sony V700 (which was copied, apparently down to the brittle plastics, in the SRH940), so the entire structure is more sound than this description might make it appear. Like I said, it managed to survive some pretty rough handling without a scratch, so I can't complain too much. I still expected more from Shure, though.
Comfort is initially sub par, on account of a bizarre design choice (or perhaps, more cynically, an example of built in upselling): the pads are quite shallow, and the material attached to the back of them that's meant to protect the driver from dirt and earwax is so thin it may as well not be there. The upshot is that the hard plastic driver guard installed to protect the driver from accidental puncture jams right up against the ear and becomes painful in under half an hour. The SRH840 pads have much thicker material (almost like cloth) attached to the back of their pads, so the driver guards on their respective model presumably don't cause this problem. Also, the headband on the SRH440 (and from what I've read, the SRH840 as well) digs uncomfortably into many people's heads.
I've solved both these problems, the first by placing a felt circle on top of each driver guard (I punched out holes for the bass reflex ports), and the second by using a piece from a velcro roll to stick some foam under the headband. With these modifications comfort is actually quite good. I can wear them for hours without any issues. As I said, I "fixed" Shure's mistakes, which I don't feel I should have had to do, given how these issues should have shown up in any reasonable product testing.
Rant over. Ergonomically I'll point out that, like several Sony monitor headphones I know of, there's only one correct way to wear the SRH440. In other words, you can't swap channels by flipping the headphone around. They seem to have a reasonable range of cup motion, so overall fit shouldn't be a problem, but I just thought I'd point out the orientation thing.
Sound
Tonal Balance
The overall balance is neutral leaning toward slightly bright. Their treble peaks aren't as tall as those of the DT880, but the overall treble level is actually slightly elevated over that of the DT880, believe it or not. Therefore, while overall they don't come across as quite as bright as the DT880, part of their EQ calibration curve (see the relevant section) involves shelving down everything above 10kHz by 3 dB.
-BASS-
Extension is somewhat lacking, but the midbass is pleasantly punchy and is very slightly bumped up. The overall character of the bass is tight, punchy, and exquisitely textured. There's a certain heft and grunt to the SRH440 bass that I find highly enjoyable.
-MIDRANGE-
Decently transparent and clear, and neither recessed nor forward. Guitars and vocals have a nice, crisp presentation, and the timbre is very natural. If I had to find a very slight fault it's that the upper mids on rare occasions can be a little shouty, but I honestly can't remember definitively the last time I experienced this. Mostly it's just an energetic, poised presentation that reminds me a lot of a nice pair of mini-monitors.
-TREBLE & EQ-
Definitely tipped up a little in overall volume, the treble is nonetheless impressively free of grain for being so prominent. Like the midrange, it carries a lot of energy and never leaves me wanting for sparkle. It also helps highlight detail without being excessive. All this said, EQ'ing out my resonance peak (6 dB at 7.6kHz), shelving down everything above 10kHz by 3 dB, and addressing a few shallow peaks at around 5.4kHz and 14kHz satisfies the perfectionist in me and achieves, to my ears, a wonderfully smooth response. Even without EQ the treble is acceptable, but it has a tendency to be edgy.
Presentation - Macro
As ever, we'll discuss soundstage, imaging, and transparency. Soundstage is one area where the SRH440 is a noticeable step down from the DT880 (since their tonal balances are quite similar). It's not horrible in absolute terms, but it's that typical "tubular" soundstage common to closed headphones: decent width, anemic depth, and no real sense of height. The effect of switching between my DT880 and SRH440 is akin to taking off your current prescription glasses and putting on the ones you used to wear one prescription ago--everything is still mostly there in the same proportions, but there's the sense that something's subtly wrong, which goes away once you've spent a little while adjusting.
Imaging is similarly very slightly lacking compared to the DT880, perhaps merely because the SRH440 has less raw space in which to distribute sonic elements. Directional cues are still obvious, but layering is noticeably less sophisticated and there's this unshakable feeling that the edges of elements are slightly blurry, compared to the razor sharp delineations the DT880 produces. Overall it's not a deal breaking step back, but it's obvious in direct comparison.
Transparency continues in the same mold. Direct comparison reveals a slight lack of refinement on the part of the SRH440 when compared with the DT880, but it's not noticeable in isolation. The SRH440 is still impressively transparent for a sub-$100 closed headphone. Veil of any kind is nonexistent.
Presentation - Micro
Detail and texture are well appointed in the SRH440. In fact, I'd say the SRH440 gets the upper hand on the DT880 here in one respect--it manages to texture its entire range, whereas the DT880 loses some texture as you descend through its bass extension. Bass in particular is very enjoyable on the SRH440 as a result of this. Detail-wise, the DT880 expectedly wins out, but it's closer than it ought to be. Both render minute artifacts and tiny details well, but the DT880 pulls ahead with its uncanny ability to convey ambiance and space around the instruments. The SRH440, perhaps being a closed design, just can't reproduce this information.
A note about the SRH840 pads
Don't do it. Easy, right? Of course I'm going to tell you why. Very simply, they change the sound quite noticeably, and not for the better, IMO. I'm also confused by the numerous claims that they somehow tame the treble, since for me they do the exact opposite. In fact, they seem to add a 5dB shelf above 5 kHz or so, a bump somewhere between 2.5kHz and 3kHz which makes vocals and guitars barky and shrill, and a mid-to-upper bass bump that muddies up the bass and makes it sound like somebody just turned on the MegaXXXXXXtraBass function on a cheap mini-system. How can pads do all this? Simple. They change the size of the acoustic chamber between the driver and your ear canal, which can have all sorts of nasty effects (see above). The SRH440 was voiced with its own pads in mind, and uncomfortable and impractical as they might be, you should leave them on there. Try the felt mod I mentioned earlier in the review. I swear it works wonders.
Conclusion
Overall, the SRH440 is an often overlooked/overshadowed headphone. Its biggest threat is probably the M50, which monopolizes all the attention whenever reasonably priced closed headphones are discussed. I've owned them both. The M50 got returned. The SRH440 is still here after two years. That doesn't mean, of course, that your preference will fall the same way. But these two headphones both deserve to be mentioned in the same sentence, and in the same recommendation thread responses. They both do a lot of things right, and they pursue slightly different tonal balances (the M50 being more focused on mid- and sub bass and less focused on midrange than the SRH440). Ultimately, the M50 had too much bass for me. If you've ever felt the same way, but otherwise liked the detail, transparency, and basic presentation of the M50, the SRH440 might be right for you.
