Youtube review: http://youtu.be/gDQXe-IFmPA
Sources: iPhone5 alone, iPhone5 with FiiO E07k using LOD, iPhone5 with Decware Zen Head amp, various computers using the Microstreamer DAC/amp.
First impressions of the RHA MA750: Very clear, detailed, very spacious, and a very impressive bass. There is an emphasis in the lower treble, similar to what I've heard with some other IEM's, but not with the pricy Sennheiser IE800. My feeling is if this adds too much intensity to the upper range of voices or instruments, it can easily be adjusted down with most modern amps and/or music players. The MA750 soundstage is typical for a good IEM, and the overall tonal qualities make the MA750 an extremely enjoyable listen. The MA750 bass is quite strong, yet it has none of the upper bass emphasis that gets muddy or adds color to the midrange. And the midrange is sublime - the overall sound is one of the best I've heard in an IEM. The MA750 fit my ear canals perfectly the first time I tried it, and doesn't tend to get loose and fall out either. The combination of a good fit with the ability to listen for hours in comfort is something I can recommend highly to anyone whose ears fit the MA750 as well as mine did.
My most recent listening has been with the v-moda M100, Beyerdynamic Custom One Pro, Sennheiser Momentum On-Ear, Bose OE2i, ATH ESW9a, B&W P7, B&O H6, and Shure SRH-1540 headphones. With the MA750 I'm hearing all of the detail I've heard with these headphones, which shouldn't be surprising since the IEM earpieces are deep in the ear canal, where the sound doesn't bounce around in the headphone earcups or get modified by the ear pinnae. Equally as important as those details are the smoothness (lack of obvious peaks or recesses) and tonal quality (lack of edgy or grainy sound, etc.) that allow hours of listening without the fatigue that can occur when such minor distortions are present. A week ago I reviewed the B&O H3 IEM which costs twice as much as the MA750, and the MA750 sounds just as good - in fact the MA750 played my music test tracks below as well as the H3, except it did much better with the Black Sabbath track.
Summing up the sound and accounting for the fact that different amps sound different (especially in bass control), I think the MA750 is excellent for jazz, acoustic, acapella, classical, and other related genres. Electronic and house music may also fare well with the MA750, but that depends mostly on whether users demand a level of bass strength and impact that goes beyond the most liberal definitions of high fidelity that I'm aware of. In other words, users who are still keenly interested in the MA750 after reading this review, but who ultimately decide on a different IEM, will likely base their final decisions on personal preference, which in many cases can be a coloration (or lack thereof) with as little difference as one decibel between the IEMs and how they reproduce those sound effects. Since the better IEMs in or near this price range are made in retail quantities in automated production facilities, personal preference is limited by the reality of what's available for purchase.
Isolation with the MA750 is very good - I would guess 20 db or more at the higher frequencies and tapering off below that. Leakage doesn't appear to be an issue, so playing music fairly loud in a quiet office in a cubicle next to other cubicles should not be a problem. The MA750 cable is sturdy-looking, about 3 mm thick, is 1.4m in length, is not detachable, and has a standard miniplug on the end. Note that the earpiece cables are designed to be worn over the ears. A clothing clip is included to keep the cable from rubbing clothing and producing excess microphonics. The MA750 comes with an impressive array of different eartip types - a total of 10 pairs. I got the best fit with the large standard tips - a smaller size of the same type was mounted on the MA750 in the package. A small stiff zippered carrycase is also included - pleather on the outside and fabric lined, with an inner pouch for extra eartips etc. This carrycase is lightweight even with the earphones inside and will fit easily into a shirt pocket.
The music tracks below were listed in three prior reviews, and are a random sample selected from the 400 most recent tracks I've acquired. Since these tracks cover a wide range of genres, and were selected when I was using several different headphones, there won't be a bias toward the MA750 with this music. My suggestion is instead of reading each comment below as an absolute unto itself, you could compare these notes to other reviews as they get posted, and see how the MA750 compares with each individual track.
Ana Victoria - Roxanne (Pop Vocal): Spacious sound, good instrumental tone - the vocal sounds very natural. Excellent reproduction by the MA750.
Ben Goldberg - Root and Branch (Jazz): Realistic you-are-there sound with great instrumental reproduction. The MA750 plays this extremely well.
Benedictines Of Mary - O Come Emmanuel (Medieval/Female Choral/Acapella): Very spacious sound and natural reverb for a large recording venue (cathedral). The MA750 makes the voices come alive.
Black Sabbath - Iron Man (Classic Rock): Excellent instrumental detail - the vocal sounds very natural. As with most classic rock tracks, there is very little or no deep bass. The MA750 plays this music very smoothly, and the lack of strong bass doesn't unbalance the treble.
Candy Dulfer - Lily Was Here (Jazz): Narrow soundstage, but excellent detailed instrumental tone. The MA750 gives this a reasonable sense of space, but in spite of being a modern recording, the net effect is only slightly better than enhanced mono.
Cantus - Danny Boy (Traditional/Male Choral/Acapella): The MA750 plays the voices with enough low end warmth and weight to sound very natural.
Chris Isaak - Wicked Game (Pop/Rock): The MA750 plays this high treble energy recording almost perfectly. The voice is too forward but tolerable, and the instruments are highly detailed but very smooth.
Daft Punk - Lose Yourself to Dance (Electronic/Disco): Less than hi-fi quality recording, but the voices are very good. There's a decent amount of bass weight, but the bass lacks detail.
David Hazeltine - Fur Elise (Jazz): A very high-quality recording from HDTracks. The MA750 reproduces the instruments perfectly with a you-are-there ambiance. The wire-brush-on-cymbal harmonics are very extended and detailed.
David Lynch-Lykke Li - I'm Waiting Here (Soundtrack/Vocal): Dark, moody song - Lykke's voice is very detailed, the strong bass impacts are very good, but most of the instrumentation is soft and kept in the background. The MA750 plays this music very well given the sonic limitations.
Dream Theater - Take The Time (Metal): The sound quality here is limited, but the MA750 is smooth enough to bring out the details in this very busy music without verging on harshness.
Genesis - Follow You Follow Me (Pop/Rock):The MA750 plays this old and less-than-ideal recording beautifully, but the soundstage is fairly narrow.
Giant Drag - Wicked Game (Pop/Rock): Annie Hardy's version of the Chris Isaak hit has a lot of energy, but the quality is limited - still the MA750 pulls out enough detail to be a pleasant listen.
Grieg (Beecham-Royal Philharmonic) - Peer Gynt-Solveig's Lullaby (Classical): This very old (1950's) stereo recording must have been made on the most expensive gear in the world, since the overall sound quality and especially Ilse Hollweg's amazing voice are as close to "being there" as I've heard with some of the better classical recordings made since the year 2000. The MA750 makes this an outstanding listen.
Hubert Kah - The Picture (New Wave): This track has great bass detail and weight at the same time, which I find unusual for this type of 1980's pop music. The MA750 plays this music very well.
Hugo Audiophile - 15-16 (Electronic): I'm not sure what the 15-16 stands for - perhaps track numbers from a CD album. The strong deep-bass tones that start around 33-34 seconds into the track reproduce well with the MA750, and have ample weight for indoor listening. In a noisy environment, especially in or near vehicle traffic or on public transport where bass is easily absorbed, the bass here will lose much of its impact. This is a perfect recording for evaluating whether an IEM's bass is tuned for high fidelity listening, or emphasized to play in venues that have an excess of ambiant low-frequency energy.
Korn - Another Brick In the Wall (Rock): Aggressive rock that's very satisfying for hard-rock fans. The MA750 plays this almost perfectly, which is to say, with proper edginess and bass impact, yet without unintended sonic harshness.
Kunika Kato - Fur Alina (Vibraphone): A very unusual instrumental - the tone quality is unlike anything I've heard before. Recording close-up is part of the magic here, but the MA750 does the rest in reproducing the full harmonics of this amazing instrument.
Michael Buble - Nice 'n Easy (Easy Listening/Jazz): This is the only track I bought by Michael Buble, but it's a great recording and vocal performance. The sound of the backing band here is rendered extremely well by the MA750, and the voice isn't pumped up for Loudness Wars thankfully.
Michael Tilson Thomas - Rhapsody In Blue (20th Century Classic): Great sound and soundstage, and terrific piano playing and tone, brought to life by the MA750. There are some very deep bass impacts here starting around 38 seconds into the 17:24 length track, but as with the Hugo Audiophile track above, the impacts have just enough weight to be appreciated in a quiet listening environment.
Muse - Madness (Rock): The bass in this track has great impact and detail with the MA750. The lead voice is forward and strong, but doesn't overwhelm the track's bass line.
Phaeleh - Afterglow (feat. Soundmouse) (Electronic/Vocal): The instrumental sounds that begin this track are played very nicely by the MA750, and the voice works well with those background sounds - until the heavy bass impacts kick in. If there is any doubt about whether the MA750 will play heavy impactful bass with good detail (if such sounds are really in the recording), this track is the proof. If you were to begin your MA750 listening with this track, you might think you were listening to an IEM that has a very boosted but tight and detailed bass. Simply amazing.
Richard Strauss (Mester-Pasadena) - Also Sprach Zarathustra (opening) (Classical): The granddaddy of bass is in the opening 1:50 of this recording, and I've heard it only once on a large and expensive loudspeaker system in Cleveland. For most people, that experience would be indistinguishable from being in a fairly strong earthquake. The MA750 conveys as much of that experience as is possible on an IEM. The tympani also have excellent impact here.
Sargis Aslamazian - The Sky is Cloudy (Classical/Armenian): The National Chamber Orchestra of Armenia has a great classical program, and the MA750 plays this music with good separation, tone, and big-orchestra precision.
Satri-Tomoko Sonoda - All The Things You Are (Jazz): This track came from Bakoon Products, who make high-quality audio amplifiers. There's a lot of upright bass plucking in this track, and the MA750 plays it well, although it's recorded pretty close-up and may sound slightly boomy at times.
Tommy Smith - Johnny Come Lately (Jazz): Small-combo jazz; sax, piano and drums. The sound is fairly close-up but well-recorded, and sounds very nice with the MA750, although the wire-brush-on-cymbal harmonics are not as extended as on the David Hazeltine track above.