Pros: Impactful bass, good midrange, good textured sound
Cons: Stock cable, comfort, highs, upper bass muddies up the sound, congested sounding sometimes
The M-Audio Q40 is the first high quality headphone I've owned, despite this I can still be honest and accurate about the qualities of this 'phone without overselling it.
Let's start with the build quality and design. The plastic that this headphone is mostly constructed out of is rigorous and it'd take quite a bit of effort to break and in no way feels cheap, brittle or flimsy. The headband is malleable to a degree, but I'd be careful and not overestimate it's flexibility or test it's limits because it's definitely capable of being bent or stretched to any head shape, --- which I've actually gotten it to do for me, despite my larger than average head. The headphone cups are good too, but honestly the additional pseudo-grills they added onto it are loose and can creek and cling sometimes when you're adjusting the headphone on your head or touch them, but for the most part aren't really noticeable or problematic in anyway. Now, here's what really urks me about these headphones; on BOTH sides of this headphone about 3.5 inchs of wire is exposed and for me I can't help but worry that one day this'll be the thing that does these headphones in. Other than that, construction is top-notch and I wouldn't expect it to break unreasonably.
Comfort is mediocre in these but not as terrible as some would like to state. Once you stretch them out a bit they actually can be worn quite easily for a few hours at a time. The pads are pretty thin and look/feel like a cheaper type of pleather but are still pleasantly soft despite being thin and aren't too bad. I'll honestly say the first time I put these headphones on I couldn't wear them for more than a few minutes without having a discomfort-caused headache, but at this point I'm accustomed to a strong clamp and they've loosened up a bit so I can't really complain.
Now on to my favorite part: The sound of these headphones.
For this part of the review I'll explain how this headphones fares in certain situations and what it's like.
So without any equalizing, the Q40 is a slightly bass-emphasized headphone with good, clean mids that are a bit less than what you'd say it 'forward' sounding, so vocals on some tracks are a bit softer sounding than the instruments but still quite clear and good sounding -- to elaborate on that, they sound very natural to me and are very pleasant. (which is unusual for bassy headphones) -- the highs are good, but there's a small 10k spike and a pretty big roll-off thereafter. I personally could do without the 10k spike (and usually do when I apply an EQ) but the rolloff for me is a big plus, because I can't stand fatiguing treble and my ears are unusually sensitive to higher frequencies. The lows are probably what most people are interested in, so I'll get right into detail with those. These headphones aren't all about mid-bass, which is probably the bass 'bassheads' per say, would be looking for. I am a self-acclaimed basshead and I know a lot of bassheads originate from a listening experience with the Sony XB-500 or Dre Beats, (I know I did --- XB-500s, not Beats, I don't even need to elaborate the silliness of the latter) which is very mid-bass heavy. The Q40s have really good sub bass, a type of bass most headphones don't even touch. Every frequency from 20 - 300 hz is at least at and/or above neutral and 50 - 100 hz is the most elevated frequencies (100 hz being the peak). 50 hz going towards 20 hz is like a slope, but it's still elevated, audible and present. Now, going past the quantities aspect, I'll start off by saying the Q40s bass is tight, very fast and well-textured. This is highly evident when listening to metal with fast, low, hard-hitting drums and these headphones really don't miss a beat. Despite the lows being highly present in this 'phone, they're very proper and not intrusive to the mids or highs and don't make a big mess of everything. Quality over quantity, a lot of people would say and prefer --- HOWEVER, the bass quantity in these headphones to me is unrivaled by most headphones and just a bit below XB-500 level, DISCLAIMER; with a bit more power than an onboard sound card or normal iPod offers they are really on-par with the XB500 (un-equalized) and with a bit of bass boost can easily rival the XB-500, not that it's necessary cause the sound of this headphone as a whole presents it's self in such a lovely fashion that much alteration isn't necessary to be satisfied.
All in all, I'd sum the sound to say they're a warm, clear, well-defined sound headphone with excellently present sub-bass and decent mid-bass. The midrange is perfect, for me, and if you get rid of the 10k spike there isn't a thing wrong with the sound of these headphones, unless you really like far-extended highs and overly bright headphones, then I guess these would feel a bit lacking in that aspect. For casual listening at home and in quieter place, there's no headphone I'd choose over these. For portable headphones and in loud places, these do work for portable headphones, but with the exposed wires and need to turn them up really loud I really find it more on the inconvenient and worrisome side.
*update, over a year later*
I've long since sold my original Q40 and bought a new one. I modded the new one with a decent amount of fiberglass and cotton, as well as replacing the stock earpads with 840 pads. Stock earpads sound best, but comfort is important too. The clamp on these headphones is a bit much for extended listening. I usually don't listen to these without equalizing down 100 - 200 hz by about 3 decibels. When equalized they're a really good sounding headphone for 100$ (what I paid the second time). They have a smallish soundstage, but when equalized like I do they have a very nice, textured sound that makes them a very fun listen, preferable sometimes to my MA900 and T50rp II. Build quality is questionable, I know the wiring is ****ty but I don't think the headphones will fall apart anytime soon. Stock cable is mediocre, it wines when plugged into my Magni. I'd say you can't go wrong at 100$, but as you get closer to 200$ there's many more options, most of which are objectively better -- though, not as much competition for a good basshead 'phone. I'd say these are clear sounding without equalization, the upper bass makes them seem muddy, though they aren't. After extensive research, I re-purchased these instead of the DT770 and I'm glad I did, aside from the comfort issues.