An expanded Pros & Cons regarding the HM9:
Pros: Very warm sound signature, so this is a pro if you're after something warm. The treble is subdued, nothing is overlly bright and there's no siblance, so if you're sensitive to treble this is something you'd appreciate. Fairly good sound stage, great set of detachable cabling, well made construction and really great fat ear pads that are thick and soft. The unit folds to a compact nature and again the cables are detachable. Great isolation (given it's compact and portable nature, this is great, as it means you can probably use it in public and it not be a waste of time).
Cons: Very warm sound signature, so this is a con if you're after something neutral or something more analytical. While it's not fair to really call this a con, I felt that it was too in between in terms of being on-ear and being over-ear, because you can certainly fit your whole ear in there unless you have wombat ears, but it's clearly meant to be smaller than over-ear cups generally are, so it's classed more in the size of on-ear (again, not fair maybe, but just had to point this out as it did bother me).
Brainwavz HM9 - Very warm, Compact and Sleek.
The vast sea of headphones these days (hey, it's not the 80's and 90's anymore for some of us, there's actually choices in headphones these days!) is nearly endless it seems, so it's hard for anyone to truly compete for attention when it comes to certain price points. When you clock in at the $100 tier of devices, you have to really have something special, or a great package, or really good marketing to get an audience. Brainwavz is really trying to do all three of these things, offering a very well made product, worth more than it's price suggests, with a very good overall package, again, making it much more attractive than some other items that just show up in a plastic wrapped thing that you have to cut open. And marketing wise, they're doing it right, they're asking the community to tell them what they think, instead of just putting them on easy-endorsement artists or sports celebrities and asking them to wear them on TV. Brainwavz is instead putting them on the heads of audiophiles, real people, and asking for their opinions. You have to respect that approach. But there is still a ton of competition in the $100 tier market. Even with their own other headphones! So it comes down to what you're looking for and if the check list ticks all the right boxes. The HM9 is a compact, portable-class headphone with all the right features: high isolation, very thick, soft ear pads and headband, folding design for compact storage, thick durable plastic so it's not heavy and won't break, detachable cables in three different lengths that are flat instead of round so they do not coil up or twist and lay flat when wearing so there's less movement and thus less sound translated from them, with a nice hard shell carry case. I've looked around, and I've yet to find very many other $100 offerings that supply you with something built as well, with excellent sound quality, that also offers meaningful accessories and features and not just a bunch of nothing, or a bunch of flash that you don't care about. Brainwavz seems to really be doing it right in this aspect.
Quick Reference for the TL;DR folks:
Thick plastic build, some metal
Entry price of $100 on average, which competes with too numerous to count options
Super warm sound signature, with very prominent bass
Relaxed, dark, fatigue-free treble
Very efficient, will run from a potato
Excellent isolation, I couldn't hear my mechanical keyboard while typing this
Flat wires, tangle free, and no transmission of noise from rubbing
Carry case, three cables, and all made very well
What Comes in the Box:
HM9 Headphone
Hard case (fits the headphone folded up, seals with zipper, has room for cables); not crush proof
Three cables: 1) 1.2m flat (portable hi-fi), 2) 1.2m round with microphone (cellphone), 3) 3.0m flat (home hi-fi)
Airplane adapter (why? A 1/4th adapter was not included, but this weird airplane adapter was)
Overall, a nice package if you want functional and useful stuff and only one minor "oops" in the airplane adapter which to me is totally not necessary and near pointless, and would have rather had a 1/4th adapter included to couple with the 3.0m cable for home use. Anyone who cares about audio will NOT be listening to an airplane's in-cabin audio, which is easily the worst audio source on the planet and mono to boot. Maybe in some other countries there is a competitive airline that wants to wow passengers with their higher quality in-cabin audio. But I've yet to be on that airline. Someone can fill me in via comments I hope. Otherwise, again, totally boggled by the inclusion of this airplane adapter. The cables are superb. The two lengths are excellent for their intended use. And the inclusion of the microphone is good for the phone-folk. The case is nice, and everything is well made. Nothing screams cheap. But hey, where's that 1/4th adapter?
Specifics (the minor numbers):
40ohm Impedance
104dB/mW Sensitivity
What does that mean? They're efficient. They will run from anything just fine. I was surprised they were even 40ohms actually as I expected something like 16ohm to 32ohm, but rather the 40ohm was odd to me, but it doesn't matter, it's just a number. The sensitivity tells you what's up, and they are efficient, so they will get loud from nearly any device. There's zero need for an amplifier here unless you're using a phone that has awful output. But this is expected from a compact-class headphone designed for portability.
Construction, Materials & Comfort:
The build of the headphone is good. It's sturdy, hard plastic, thick where it should be and doesn't creak or crumble. The headphone and ear pads are very thick and soft, like memory foam. They remind me of the old Sony XB pads, super thick and plush. The overall design is just a flat silver and matte black, nothing shiny which is good. No blaring logos either, it's rather subtle in general, which I really respect. Comfort is surprisingly good to me, as I normally cannot stand on-ear design headphones. While these are in-between that, with a size that could be over-ear for many people, but still on-ear for some others, it's a hybrid zone where it swings either way. It worked for me because I could squeeze in and get the over-ear feel and sound that I prefer, as I do not like on-ear in general for comfort purposes. The headband squeeze is not too tight, but it's not loose, just right to me. The pads really are comfortable. They are pleather, so if you're out in the sun, you will get sweaty. But just sitting inside some where, I found them to breath enough to not turn into little ovens, so that was nice.
Sound Characteristics:
I'm a fan of the warmer sound of headphones, as I'm not into the analytical approach for everything, though I like it sometimes, it's not my go-to for at-home-listening. The HM9 is definitely a warm headphone, nearly to a fault. So keep this in mind if you're someone who can't stand very warm headphones, the HM9 is not for you. But for those of you who want a very warm, very lush sound with fatigue-free treble, the HM9 might speak your language. When I first started listening, and then weeks later, the experience was the same for me: lots and lots of mid-bass, upper bass, lower mids. That translates to a lot of warmth. Everything is warm no matter what you do straight out of the box. The treble is fatigue free, which is very nice when you're turning it up, but I found it to be a little on the dark side compared to my tastes (takes that edge out of violin that is supposed to sting a bit, and some piano strikes), but at the same time, zero siblance or hissing so that's great for others. The mids are decent, but definitely a bit recessed, and a touch distant, it reminded me of a recording where the artist was coming through a cloth first, then the blocker in front of the microphone, which takes more of the tiny nuances away from consonant production, but I'm being picky. Vocals were clear, but let's just say I wanted more clarity. When I put on some tracks that were rich with mid-bass content I noticed the congestion built up quickly, which is common for very warm headphones.
Treble:
The HM9 is fatigue free with treble, you will have no issues with siblance or hissing sounds. It's not quite as dark as something perhaps like the HD650 level of dark, but you get the idea. It's not going to scratch your ears out with treble spikes, like an Ultrasone. So this is a mellow listen from a treble stand point. This is good if you're particularly sensitive to treble. But it can be an issue if you're into certain detail retrieval and want that sting from certain sounds. For me, violin and piano really didn't have the edge that it normally would have, because the treble roll off was significant. This will make it seem like it's less detailed, but that's not the case, it's just less intense. When you couple subdued treble with increased bass, the end result is super warm sound which may or may not be your cup of tea.
Mids:
Mids are pretty much the most important bulk of any range in audio for us, because that's the heart and soul of our natural vocal range, instrument range, etc in terms of the bulk of the average we can hear and while hearing bass & treble changes with our years on this planet, the mids don't change quite as significantly, so mids are critical to get right. The HM9 has ok mids. I was not truly impressed with the range or clarity. I found too much bass bleed, from the massive warmth, to the point where the mids were congested to me, and distant to a degree. I felt like I was being lulled through a cloth in many ways. Mids are a touch recessed, with the massive warmth from the mid-bass. I through on some very fast music with lots of electric guitar and blast beats to test the speed of the HM9 and found it very congested, as a lot of this is in the mid-range, or bleeds into it. So keep this in mind. If you're a mids-head and seek super clarity, the HM9 is not for you. If you're into gobs of warm bass, and fatigue free treble, this will work out for you likely.
Bass:
These days, bass seems to be super important. I guess it's cultural. I say that as a reverend bass-head myself. I don't always want too much bass. That said, I appreciate quality bass that is well controlled and doesn't just roll off steeply. You'll find the HM9 has a lot of mid-bass and upper bass. It's very warm. No matter what you're listening to, there will be a lot of emphasis on the upper end of bass, to the point of it bleeding into the mids significantly. If you're all about the mid-bass, which there are genres for that, then this may just be what you're after. I found the sub-bass to not have received the attention that the mid-bass received, and the sub-bass is significantly rolled off. I tested some dub just to see if it could land a satisfying 25~30hz drop, and it was not intense and felt distant and loose compared to the mid-bass. Mid-bass can slam your face off though, so if you're into hardcore or other genres with gobs of mid-bass, this will shake your head sufficiently. If you're not into bass and warmth, and seek neutrality, this is not for you at all.
Isolation:
The HM9 delivers nicely with isolation. While it's passive isolation, I found it still did it quite well. While it will not block out a city buss next to you, nor an airliner, and it certainly won't stop the pulses inside an MRI machine, it will at least block out typical noise that would be distracting. I couldn't hear my mechanical keyboard clacking away while I typed this, while listening to music through the HM9 at normal listening volume. That's fantastic. So that means you won't hear non-yelling conversations out in public, or someone's phone conversation, or someone's loud earbuds buzzing in their ear next to you. On this note, the cable doesn't transmit audible noise to you, which is a big deal to me. I can rub the cable on my shirt and I don't hear the vibration or noise, so that's great. Helps you with the idea of isolation when the cable is moving as you walk around as these are portable headphones.
Soundstage:
I don't expect a lot from closed headphones for soundstage, if you are reading it as a term of width or spaciousness. It's a closed stereo headphone, so it's not like an HD800. The soundstage is pretty normal to me, not too terribly closed in, but not as wide as something open air. I found it to be fine, and normal enough to where it didn't distract me. There are some that are so narrow in soundstage that it sounds like there's no distance between anything and gives it a flat feel. If you're reading it as soundstage as a term referring to separation of notes, then it has decent soundstage in that regard. Though I found it muddled in several places where the bass-bleed really slowed and congested the mids. I found the aggressive mid-bass hump really took the soundstage (read as separation) down significantly as the intensity of the complexity of a track increased. Translation: if you're listening to metal, you'll find it hard to hear clear separation of instruments. If you're listening to electronica, you probably won't notice as much.
Closing Thoughts:
Overall, I think the HM9 delivers in many ways, but it has some issues that to me are hallmark of today. I think the package is great, you get the right accessories and the headphone itself is well made and comfortable. My one packaging negative mark is the lack of the 1/4th adapter, but a weird airplane adapter was included (seriously who plugs into an airline in-cabin audio system these days?). The case and cables are very good. Pads are wonderful. The other issue that I consider common and hallmark of today's mainstream culture is that these headphones are too warm, too much mid-bass, and it bleeds significantly into the mids. I know there's a big market for this sound. Lots of bassheads will enjoy this headphone. But in the high fidelity crowd, this will be something that is not overlooked and will be a big negative. I'm a basshead, and even I wasn't keen on the mid-bass hump on the HM9. I much prefer sub-bass prominence, and the HM9 has rolled off sub-bass compared to it's very strong mid-bass. I prefer the opposite, as I prefer more sub-bass, and less mid-bass, to avoid bleeding it into the mids and congesting the overall separation and clarity. So take my opinion with that in mind. The treble is too tame for me, but for others it will work well, as I know many are sensitive to peircing treble. It's just a hair too dark for me.
I took a minute to equalize this headphone to something that sounded more neutral to me, and it instantly cleared up the congestion. It was definitely the mid-bass. Way too much prominence of mid-bass and it slowed down the driver recovery and goes muddy. I pulled it back about -6db and clarity came forward quite strikingly. Overall, I dropped 156hz through 440hz by any where from -2 to -6db to round down the mid & upper bass and into the lower mids to get rid of the bleed, and it was still a very warm bassy sound but with much improved mids and clarity. I spiked treble from 3.5khz to 10khz by +2 to +8db and found it having a bit more edge and gave life back to violin and other sounds like that which pierce and are meant to.
If you are after a portable, sleekly made bassy headphone, this may be right for you if you're sensitive to treble. It comes with a great package and is made very well.
Ultimately I think there's a lot of competition out there, and the HM9 has a very hard battle to fight. The HM5 to me is superior, and the S5 is superior. I think the HM9 speaks to a certain crowd and will speak well to them. But ultimately at this $100 price tier, there's just too much to compete with and the HM9 doesn't climb above the well-known ones with superior audio (but does have superior accessories and build).
Very best,
Pros: Very warm sound signature, so this is a pro if you're after something warm. The treble is subdued, nothing is overlly bright and there's no siblance, so if you're sensitive to treble this is something you'd appreciate. Fairly good sound stage, great set of detachable cabling, well made construction and really great fat ear pads that are thick and soft. The unit folds to a compact nature and again the cables are detachable. Great isolation (given it's compact and portable nature, this is great, as it means you can probably use it in public and it not be a waste of time).
Cons: Very warm sound signature, so this is a con if you're after something neutral or something more analytical. While it's not fair to really call this a con, I felt that it was too in between in terms of being on-ear and being over-ear, because you can certainly fit your whole ear in there unless you have wombat ears, but it's clearly meant to be smaller than over-ear cups generally are, so it's classed more in the size of on-ear (again, not fair maybe, but just had to point this out as it did bother me).
Brainwavz HM9 - Very warm, Compact and Sleek.
The vast sea of headphones these days (hey, it's not the 80's and 90's anymore for some of us, there's actually choices in headphones these days!) is nearly endless it seems, so it's hard for anyone to truly compete for attention when it comes to certain price points. When you clock in at the $100 tier of devices, you have to really have something special, or a great package, or really good marketing to get an audience. Brainwavz is really trying to do all three of these things, offering a very well made product, worth more than it's price suggests, with a very good overall package, again, making it much more attractive than some other items that just show up in a plastic wrapped thing that you have to cut open. And marketing wise, they're doing it right, they're asking the community to tell them what they think, instead of just putting them on easy-endorsement artists or sports celebrities and asking them to wear them on TV. Brainwavz is instead putting them on the heads of audiophiles, real people, and asking for their opinions. You have to respect that approach. But there is still a ton of competition in the $100 tier market. Even with their own other headphones! So it comes down to what you're looking for and if the check list ticks all the right boxes. The HM9 is a compact, portable-class headphone with all the right features: high isolation, very thick, soft ear pads and headband, folding design for compact storage, thick durable plastic so it's not heavy and won't break, detachable cables in three different lengths that are flat instead of round so they do not coil up or twist and lay flat when wearing so there's less movement and thus less sound translated from them, with a nice hard shell carry case. I've looked around, and I've yet to find very many other $100 offerings that supply you with something built as well, with excellent sound quality, that also offers meaningful accessories and features and not just a bunch of nothing, or a bunch of flash that you don't care about. Brainwavz seems to really be doing it right in this aspect.
Quick Reference for the TL;DR folks:
Thick plastic build, some metal
Entry price of $100 on average, which competes with too numerous to count options
Super warm sound signature, with very prominent bass
Relaxed, dark, fatigue-free treble
Very efficient, will run from a potato
Excellent isolation, I couldn't hear my mechanical keyboard while typing this
Flat wires, tangle free, and no transmission of noise from rubbing
Carry case, three cables, and all made very well
What Comes in the Box:
HM9 Headphone
Hard case (fits the headphone folded up, seals with zipper, has room for cables); not crush proof
Three cables: 1) 1.2m flat (portable hi-fi), 2) 1.2m round with microphone (cellphone), 3) 3.0m flat (home hi-fi)
Airplane adapter (why? A 1/4th adapter was not included, but this weird airplane adapter was)
Overall, a nice package if you want functional and useful stuff and only one minor "oops" in the airplane adapter which to me is totally not necessary and near pointless, and would have rather had a 1/4th adapter included to couple with the 3.0m cable for home use. Anyone who cares about audio will NOT be listening to an airplane's in-cabin audio, which is easily the worst audio source on the planet and mono to boot. Maybe in some other countries there is a competitive airline that wants to wow passengers with their higher quality in-cabin audio. But I've yet to be on that airline. Someone can fill me in via comments I hope. Otherwise, again, totally boggled by the inclusion of this airplane adapter. The cables are superb. The two lengths are excellent for their intended use. And the inclusion of the microphone is good for the phone-folk. The case is nice, and everything is well made. Nothing screams cheap. But hey, where's that 1/4th adapter?
Specifics (the minor numbers):
40ohm Impedance
104dB/mW Sensitivity
What does that mean? They're efficient. They will run from anything just fine. I was surprised they were even 40ohms actually as I expected something like 16ohm to 32ohm, but rather the 40ohm was odd to me, but it doesn't matter, it's just a number. The sensitivity tells you what's up, and they are efficient, so they will get loud from nearly any device. There's zero need for an amplifier here unless you're using a phone that has awful output. But this is expected from a compact-class headphone designed for portability.
Construction, Materials & Comfort:
The build of the headphone is good. It's sturdy, hard plastic, thick where it should be and doesn't creak or crumble. The headphone and ear pads are very thick and soft, like memory foam. They remind me of the old Sony XB pads, super thick and plush. The overall design is just a flat silver and matte black, nothing shiny which is good. No blaring logos either, it's rather subtle in general, which I really respect. Comfort is surprisingly good to me, as I normally cannot stand on-ear design headphones. While these are in-between that, with a size that could be over-ear for many people, but still on-ear for some others, it's a hybrid zone where it swings either way. It worked for me because I could squeeze in and get the over-ear feel and sound that I prefer, as I do not like on-ear in general for comfort purposes. The headband squeeze is not too tight, but it's not loose, just right to me. The pads really are comfortable. They are pleather, so if you're out in the sun, you will get sweaty. But just sitting inside some where, I found them to breath enough to not turn into little ovens, so that was nice.
Sound Characteristics:
I'm a fan of the warmer sound of headphones, as I'm not into the analytical approach for everything, though I like it sometimes, it's not my go-to for at-home-listening. The HM9 is definitely a warm headphone, nearly to a fault. So keep this in mind if you're someone who can't stand very warm headphones, the HM9 is not for you. But for those of you who want a very warm, very lush sound with fatigue-free treble, the HM9 might speak your language. When I first started listening, and then weeks later, the experience was the same for me: lots and lots of mid-bass, upper bass, lower mids. That translates to a lot of warmth. Everything is warm no matter what you do straight out of the box. The treble is fatigue free, which is very nice when you're turning it up, but I found it to be a little on the dark side compared to my tastes (takes that edge out of violin that is supposed to sting a bit, and some piano strikes), but at the same time, zero siblance or hissing so that's great for others. The mids are decent, but definitely a bit recessed, and a touch distant, it reminded me of a recording where the artist was coming through a cloth first, then the blocker in front of the microphone, which takes more of the tiny nuances away from consonant production, but I'm being picky. Vocals were clear, but let's just say I wanted more clarity. When I put on some tracks that were rich with mid-bass content I noticed the congestion built up quickly, which is common for very warm headphones.
Treble:
The HM9 is fatigue free with treble, you will have no issues with siblance or hissing sounds. It's not quite as dark as something perhaps like the HD650 level of dark, but you get the idea. It's not going to scratch your ears out with treble spikes, like an Ultrasone. So this is a mellow listen from a treble stand point. This is good if you're particularly sensitive to treble. But it can be an issue if you're into certain detail retrieval and want that sting from certain sounds. For me, violin and piano really didn't have the edge that it normally would have, because the treble roll off was significant. This will make it seem like it's less detailed, but that's not the case, it's just less intense. When you couple subdued treble with increased bass, the end result is super warm sound which may or may not be your cup of tea.
Mids:
Mids are pretty much the most important bulk of any range in audio for us, because that's the heart and soul of our natural vocal range, instrument range, etc in terms of the bulk of the average we can hear and while hearing bass & treble changes with our years on this planet, the mids don't change quite as significantly, so mids are critical to get right. The HM9 has ok mids. I was not truly impressed with the range or clarity. I found too much bass bleed, from the massive warmth, to the point where the mids were congested to me, and distant to a degree. I felt like I was being lulled through a cloth in many ways. Mids are a touch recessed, with the massive warmth from the mid-bass. I through on some very fast music with lots of electric guitar and blast beats to test the speed of the HM9 and found it very congested, as a lot of this is in the mid-range, or bleeds into it. So keep this in mind. If you're a mids-head and seek super clarity, the HM9 is not for you. If you're into gobs of warm bass, and fatigue free treble, this will work out for you likely.
Bass:
These days, bass seems to be super important. I guess it's cultural. I say that as a reverend bass-head myself. I don't always want too much bass. That said, I appreciate quality bass that is well controlled and doesn't just roll off steeply. You'll find the HM9 has a lot of mid-bass and upper bass. It's very warm. No matter what you're listening to, there will be a lot of emphasis on the upper end of bass, to the point of it bleeding into the mids significantly. If you're all about the mid-bass, which there are genres for that, then this may just be what you're after. I found the sub-bass to not have received the attention that the mid-bass received, and the sub-bass is significantly rolled off. I tested some dub just to see if it could land a satisfying 25~30hz drop, and it was not intense and felt distant and loose compared to the mid-bass. Mid-bass can slam your face off though, so if you're into hardcore or other genres with gobs of mid-bass, this will shake your head sufficiently. If you're not into bass and warmth, and seek neutrality, this is not for you at all.
Isolation:
The HM9 delivers nicely with isolation. While it's passive isolation, I found it still did it quite well. While it will not block out a city buss next to you, nor an airliner, and it certainly won't stop the pulses inside an MRI machine, it will at least block out typical noise that would be distracting. I couldn't hear my mechanical keyboard clacking away while I typed this, while listening to music through the HM9 at normal listening volume. That's fantastic. So that means you won't hear non-yelling conversations out in public, or someone's phone conversation, or someone's loud earbuds buzzing in their ear next to you. On this note, the cable doesn't transmit audible noise to you, which is a big deal to me. I can rub the cable on my shirt and I don't hear the vibration or noise, so that's great. Helps you with the idea of isolation when the cable is moving as you walk around as these are portable headphones.
Soundstage:
I don't expect a lot from closed headphones for soundstage, if you are reading it as a term of width or spaciousness. It's a closed stereo headphone, so it's not like an HD800. The soundstage is pretty normal to me, not too terribly closed in, but not as wide as something open air. I found it to be fine, and normal enough to where it didn't distract me. There are some that are so narrow in soundstage that it sounds like there's no distance between anything and gives it a flat feel. If you're reading it as soundstage as a term referring to separation of notes, then it has decent soundstage in that regard. Though I found it muddled in several places where the bass-bleed really slowed and congested the mids. I found the aggressive mid-bass hump really took the soundstage (read as separation) down significantly as the intensity of the complexity of a track increased. Translation: if you're listening to metal, you'll find it hard to hear clear separation of instruments. If you're listening to electronica, you probably won't notice as much.
Closing Thoughts:
Overall, I think the HM9 delivers in many ways, but it has some issues that to me are hallmark of today. I think the package is great, you get the right accessories and the headphone itself is well made and comfortable. My one packaging negative mark is the lack of the 1/4th adapter, but a weird airplane adapter was included (seriously who plugs into an airline in-cabin audio system these days?). The case and cables are very good. Pads are wonderful. The other issue that I consider common and hallmark of today's mainstream culture is that these headphones are too warm, too much mid-bass, and it bleeds significantly into the mids. I know there's a big market for this sound. Lots of bassheads will enjoy this headphone. But in the high fidelity crowd, this will be something that is not overlooked and will be a big negative. I'm a basshead, and even I wasn't keen on the mid-bass hump on the HM9. I much prefer sub-bass prominence, and the HM9 has rolled off sub-bass compared to it's very strong mid-bass. I prefer the opposite, as I prefer more sub-bass, and less mid-bass, to avoid bleeding it into the mids and congesting the overall separation and clarity. So take my opinion with that in mind. The treble is too tame for me, but for others it will work well, as I know many are sensitive to peircing treble. It's just a hair too dark for me.
I took a minute to equalize this headphone to something that sounded more neutral to me, and it instantly cleared up the congestion. It was definitely the mid-bass. Way too much prominence of mid-bass and it slowed down the driver recovery and goes muddy. I pulled it back about -6db and clarity came forward quite strikingly. Overall, I dropped 156hz through 440hz by any where from -2 to -6db to round down the mid & upper bass and into the lower mids to get rid of the bleed, and it was still a very warm bassy sound but with much improved mids and clarity. I spiked treble from 3.5khz to 10khz by +2 to +8db and found it having a bit more edge and gave life back to violin and other sounds like that which pierce and are meant to.
If you are after a portable, sleekly made bassy headphone, this may be right for you if you're sensitive to treble. It comes with a great package and is made very well.
Ultimately I think there's a lot of competition out there, and the HM9 has a very hard battle to fight. The HM5 to me is superior, and the S5 is superior. I think the HM9 speaks to a certain crowd and will speak well to them. But ultimately at this $100 price tier, there's just too much to compete with and the HM9 doesn't climb above the well-known ones with superior audio (but does have superior accessories and build).
Very best,
I'm assuming that the airline adaptor is one of those two prong ones similar to this (http://www.amazon.com/Parts-Express-Airline-Headphone-Adapter/dp/B002I9WCWK)? I do a lot of long haul travel (10 hour plus - business class) - and they come in pretty handy if you're watching in flight movies, and want to use a decent set of headphones. I often use an adaptor with my IEMs for this exact use.