The RHA S500/S500i is a surprisingly impressive IEM in a small form factor, given its many shortcomings, which I will cover in this review. The micro dynamic driver is stationed in full aluminium housings, with a combination of fabric and rubber cabling, ending in an aluminium straight plug.
 

 
Packaging and accessories are adequate; a luxurious presentation with hearty content to back up the main show. Inside, one will find a nice, foamy netted carrying pouch, shirt-clip, and 7 pairs of RHA's "dual density" silicone eartips. There are two variations of eartips with slightly different shapes: one is like an olive, and the other is a sphere cut in half. This variety should accommodate most ear canals without issue. If you do have your own favourite tips, use them instead to get the best isolation and fit. While the single piece aluminium looks eye-catching and futuristic, the minimalist design failed to account for the sharp metal edges that can come in contact with your ears and cause strain. I find it less of a flaw when worn cable around the ear, but nonetheless it is to be noted.
 

 
In my many past experiences with IEMs using fabric cabling, it usually resulted in unbearable microphonics and tangling issues. RHA did things right by mixing the two, with the Y-Splitter dividing the materials used. Even though the part of the cabling from the splitter to the housings are rubber, there is still a substantial amount of microphonic, which can be helped by wearing the cables over the ears coupled with a shirt clip, but not too much. Thus, exercising with these are not recommended. The slider is a snap-on type, which is obnoxious and useless as it is very easy for it to snap off, forcing the user having to adjust and clasp it together again. The cable's fabric feels rather cheap and fragile, and is undoubtedly prone to fraying. Strain relief appears to be sufficient, but within the first week of moderate usage, wear marks were already noticeable at the ends of the cable. The overall build quality is not too bad, and it should be fine as long as you're not using them for physical activity.
 


I found the stock tips to be quite underwhelming, and used Sony hybrid and Monster triple-flange tips with it instead, both of which gave me a perfect seal and fit. While the sound quality is superb for the size and the price, its many shortcomings will certainly fend many people off. To start with, the bright fatiguing V-shaped signature is quite prominent, with somewhat washed out mids. Sibilance and driver flex is always an issue, and tend to happen very often, even after 200 hours of burn-in. I did an exchange after a week, and much to my surprise, the new one had the same issue as soon as I took it out of the box. It can be extremely annoying when this occurs at random. Isolation is poor, as there is a tiny hole at the bottom near the cable end. The included microphone in the i model seems to be of very poor quality. Whilst on a call with a friend, background and wind noise was a constant complaint. Instrumental separation, resolution, and soundstage imaging are all very impressive for the asking price; I was surprised to hear all the details and notes in what I've thrown at it, as the S500 can effortlessly reproduce the sound files to its most neutral state.
 
All in all, the S500 is a very promising IEM, but the many drawbacks I've mentioned make it a deal-breaker for me. For only $10 more, the S500i version includes an Apple 3-button remote control, which is very appealing for Apple users as an upgrade from the EarPods. If you can oversee the aforementioned issues, the S500/S500i is without a doubt a decent investment, starting at only $39.95, which includes the lengthy 3-year international warranty.
 
I'll be updating this review with a comparison to the Zero Audio Carbo Tenore soon, which I find is the closest competitor to the S500.

 
Pros: Build quality; Strong bass presence.
Cons: Driver flex - makes positioning finicky; Sibilant; Scooped out lower midrange.
Tonal Balance: V-Shaped (Enhanced bass and upper midrange)
Style: Worn down IEM
Cost at Time of Review: $40 for non mic, $50 for mic
 

Reviewing Process

The RHA S500i have been my daily driver through my iBasso DX90 for approximately 1 month now. I’ve almost exclusively used them with the DX90 and no need for additional amplification. I’ve spent enough time with the S500i that I feel comfortable sharing my opinions on their sound and build. Even so, this is a subjective review and reviews will never trump experience. Test out headphones whenever possible before purchasing them!
 

Build & Fit

Build
The housing is tiny, machined of lightweight aluminum alloy without a weak spot visible. The housings are denoted L or R to easily distinguish which side is which. The cable seems adequately built with adequate stress relief on either end, terminating in a rugged feeling aluminum alloy 3.5mm jack. The remote feels higher-quality than most in this pricerange, no looseness felt on the buttons and the microphone sounded quite clear for cell phone usage. Budget in price, but solid in feel.
 
Fit
The fit is not particularly noted as comfortable, but I’ve had no issues wearing these for 2 hours at a time. Insertion is simple, though finicky to get a proper sound and driver flex is a part of the issue. The driver flex is not severe, but certainly heard when forming a seal and creates a bit of an issue in obtaining optimal sound from the S500i. A plethora of tips should ensure a solid fit for most.
 

Sound Quality

Bass
The S500i prominently displays the bass, often being the forefront of the sound regardless of the genre. They dig deeply with somewhat decent speed and decay, though somewhat loose and untextured throughout. They’re not as pushy and bloated as the Xiaomi Piston 2, but the bass is average for the price in all but presence.
 
Mids & Highs
The lower-midrange is prominently recessed; sandwiched in between prominent bass and shouty upper-midrange that simply amplifies this recession. This gives lower-ranged vocals, lower to mid-ranged piano notes and lower to mid-ranged guitar notes a feeling of being drowned out. In a vacuum the midrange sounds rather clean and enjoyable, but the moment other instruments enter, the lower-midrange takes a big step back.
 
The upper-midrange does nothing to hide sibilance, and when sibilance isn’t an issue I find this frequency range to be shouty and somewhat grainy. There’s a distinct lack of balance between the lower-midrange and the upper-midrange that creates a very uneven volume level between the two frequency ranges, especially as singers vocals climb in range.
 
The treble is present, somewhat grainy and fuzzy, similar to the bass in regards of texture. Having a rather generic splash for cymbals rather than showing each type of cymbal’s distinct tone and texture. Treble is present though, without being harsh.
 
Presentation
Width is respectable for an IEM, though the depth is rather unremarkable - I get no sense of distance from front to back. Imaging is also rather unremarkable, a simple left and right is noticed, but the sound is presented rather flatly. Congestion is also a concern and is mostly an issue of bass bloom and the shoutiness from the upper-midrange. There is no real sense of hard edges to the instruments with the S500i.
 

Conclusion

Man, it really seems like I hate the S500i yeah? I really don’t, and perhaps I’m being overly critical of them. I actually like the S500i more than most of the budget IEMs that I’ve heard, much better than the Piston 2, for instance, but they do have pretty notable flaws that I can not gloss over. At the end of the day the S500i are a budget IEM and they are certainly going to have compromises by design - but for a $40 IEM (without microphone) they have been a nice daily driver for the past month.
 
Now the question is do I recommend these? Given a 3 year warranty and a plethora of accessories the S500i are a solid buy for those who want a strong bass response and the security of a reputable company backing them.

Introduction

First, I would like to say thank you for RHA Audio providing the s500i headphones as a review sample. The opinions are my own, and not supported by any review sample related euphoria, even though these were the first review samples I ever received.
 
This is a dual review of the RHA s500i and the RHA ma750.
 

Fit and Finish

As they always do, RHA audio sent a loaded up sexy looking package for the s500i. They even gave me three windows to see into that beautiful cardboard house, two for the headphones, with a tastefully placed divider around the midsection, and one for all the ear jewelry. In all there are 7 pairs of silicone tips: 2 each of small, medium, and large single flange designs, and one set of double flange silicone tips. The tips include a plastic insert that is really useful for keeping your tips from floating about. Also included inside the box were a small mesh pouch and a shirt clip. The insert does not fit in the pouch. It would have been a nice touch. Next time, RHA, next time.
 
I didn’t get the ma750 at retail, I borrowed them from a friend and then worked out a deal to keep them. They were my daily drivers from late November to early January. The ma750 comes with even more tips in a swish metal insert inside a nice rectangle carry case. The ma750 also comes with foamies, which many will like, but I find I only like when I really need to shut out ambient noise. Foamies colour bass sound, in my opinion, and I become too aware of their presence.
 
The cable and in line remote on the s500i have nice quality and texture. I didn’t use the in-line remote as I don’t have an iPhone and generally control my music with my DAP or computer+DAC. The ma750 has a rugged stainless steel capsule that looks bomb proof. It comes with built in ear hooks. I found that the ear hooks were a bit too floppy, making it difficult to wear the headphones with the cable behind the neck. I didn’t notice any problems with microphonics with either cable, but I also didn’t break into a sprint at any point during my review. Most of my time was spent sitting at fake wooden desks typing away at keyboards as I am now.
 
A note on RHA tips: they rock. I found they give a good seal, good isolation, and a balanced presentation. Don’t change your silicone tips for nobody, RHA.
 
 

Comfort

These microdrivers are miniscule. They weigh next to nothing. I found them most comfortable worn down. It is possible to wear them up, but it feels strange. Worn down they settle right into the crook of the ear. I really like the RHA silicone tips.
 

Sound

I have conflicted emotions about how these sound. They make me realize that I may not be a one headphone man—I know, funny for someone in this hobby to say that. I started out on HeadFi as a lurker in 2009, looking for the one set of IEMs that would satisfy my every need for the price that I could pay, I got the HiFiMan RE0 off of |joker|’s recommendation, and I was quite satisfied. I bought a Cowon D2+ off of HeadFi recommendations later that year.  That combination sated me for four years—until I figured out that I can’t wear IEMs for 8 hours a day at work. My ears won’t tolerate it, and that is when I got a set of overears. The KRK KNS8400 on HeadFi recommendations and wrote my first review on HeadFi, a three-way review between the KRK KNS8400, the RE0, and the Shure SR440. The KRK was for one purpose: work. When I bought my third set of headphones, it was the HD600, and they also had one purpose, listening at home. I’ve only ever owned headphones for a single purpose until this year. These headphones are part of a realisation, to paraphrase Marshawn Lynch’s favourite candy, that there is a whole rainbow of aural pleasures to sample out there. It’s time to hear the rainbow.
 
I’ll say it up front, before I got these headphones I had a bit of an infatuation with their older sister, the RHA ma750. She had been my daily driver for two weeks and I was beginning to get comfortable cozied up in her sonic curves. The ma750 is a fat bottomed girl, and they do make the rocking world go round. When coming from the luscious bass with sweet funky tone of the ma750 the s500i sounded thin, distant, cold and metallic. It was shocking. I liked elements of the sound. I’d been listening to analytical headphones with the RE0 before, but I found that I’d become accustomed to the more coloured coiffure of the ma750. I came to the conclusion that these sounded great, but that I wanted to spend my time with a fat-bottomed girl, not the Thin White Duke. This was before Christmas, and I hadn’t listened to any Bowie while I was taking my review notes.
 
I started writing this review yesterday (Jan 18, 2016), and stared down at my notebook of audio insights and saw that in spite of listening to the s500i for nearly 40 hours, I’d stopped taking notes at two pages. I had ten pages on the ma750 from my listen with the Lotoo Paw 5000 review unit. I really hadn’t given these a fair listen. I had reached a conclusion about the ending while the story was still unfurling. I hadn’t listened to Bowie. David Bowie, whose echoing voice in Ziggy Stardust first told me what a good pair of headphones can be when I plugged the RE0 into my Cowon D2+.
 
I played Ziggy’s guitar through the s500i for obvious reasons. Listening to Black Star was a cathartic goodbye from Bowie over the last week. It felt like Bowie was giving his own eulogy at a funeral that all of us were attending. It was a deeply personal and deeply public goodbye. Who but Bowie could turn their own death into an artistic masterpiece?
 
I put on Ziggy, the incarnation of Bowie that I first fell in love with. I took out my pen and notebook, and wrote down what I felt about the RHA sisters, playing them back to back, examining their curves, their sharp cheek bones, their sway under the serious moonlight. I didn’t just listen to Bowie, I said hello to Freddy, too. Roger Waters, Charles Mingus, and Regina Spektor joined the party for a bit.
 
The s500i takes more convincing to show her personality. I don’t think I understood that when I first played her. I didn’t do much adjustment for comparative volume on my first forty hours of listening. The s500i likes to be driven hard. On the DX50, I routinely had the volume 9-10 points higher for the s500i while comparing to the ma750. The s500i really likes it when you crank up the volume. Similar differences were found on the Geek Out V2.
 
I put ‘Space Oddity’ on. The s500i has tight well defined bass, while the ma750 is a bit more funky. The s500i has precision, and razor details. The ma750 has ambience, theatrics, a hint of sugar in the vocals. The s500i sounds more natural with Bowie’s vocals. Both are airy, but the s500i sounds cleaner, a little colder. There is a little bit of a metallic sound to some of the treble, and I suspect it’s partly due to the aluminum capsule (I still can’t bring myself to say aluminium after 4.5 years in England). I find myself preferring the s500i in everything but the treble presentation. Some highs are a bit piercing, and there is a touch of tin in the cymbals.
 
On ‘Fat Bottomed Girls’ the drums kick a touch reluctantly and without sufficient conviction with the s500i. Clapping hands sound great, but the tin remains in the cymbals. These s500i like big drums, but can be a bit recessed on more mid-sized drum offerings. The ma750 is fuller and more forward. The details seem to come at you with more force with the ma750. There is an ambient dimensionality, the soundscape sounds full and broad on the ma750. Cymbals have their proper shimmer. The texture of the drums after ‘big big woman...’ is more pronounced and more convincing. Advantage ma750. Mounting up for ‘Bicycle Race’, the ma750 maintains its advantage. It sounds more dynamic and engaging. The musicality and warmth of the ma750 pair well with the music.
 
Switching to female vocals, I summon up Regina Spektor – Fidelity. The s500i wins this round. It has a natural vocal weight with no added thickness. The ma750 colours Regina’s voice making it thicker and more weighty. The sound is clearer on the s500i.
 
On Roger Waters – Late Home Tonight, Part One; the presentation of the street scene versus the sound inside the home and the impact of the bomb is better deployed on the ma750. The s500i has clearer details, a clearer and more forward representation of the fighter jet approach and more natural treble feel on the violins. Slight edge to the s500i.
 
Charles Mingus is my favourite jazz musician. The ma750 did his song, ‘Ecclusiastics’, better. The tone was richer, with more full tone on piano. The horns sound better for the s500i. Both headphones show some recording noise, but the sound is more forward on the ma750.
 
Returning to David Bowie – Moonage Daydream, the contest is a push again. The s500i has a more visceral razor sharp feel to guitars, but doesn’t have as much impact on drums. The drums impact like Tommy Gun rounds for the ma750. There is a touch of sweetness in the vocals of the ma750. Piano sounds clearer and spacing of instruments is more apparent on the s500i.
 
While writing this review I listened to Best of Bowie, and Black Star exclusively with the s500i. I never felt like I needed to switch to the ma750. The s500i has a leaner sound, but it isn’t thin. The leanness leads to some details showing up better. The bass is tighter and more focused than the ma750. In terms I heard about the RE0, it has good bass quality, but unlike the RE0, it has a decent quantity too. The treble presentation, can be a little fatiguing over time.
 

Conclusion

Both of these headphones are fantastic value, and I find that they are like two flavours out of one delicious bag of skittles. After giving myself some time for perspective, and getting to know the s500i outside of the formidable shadow of her big sister, I found myself really appreciating her unique qualities. At £29 the s500 (mic-less version) has no right to sound as good as it does. It is detailed, with tight accurate bass, airy soundstage, and great visceral texture on guitars. Instruments are well spaced and generally well-played. I give the s500i a 4.25--HeadFi, your rating system isn't sensitive enough, either go to 10, or do 1/4 points.
 
The ma750 is a worthy headphone to step up to, but double the cost. It has a fuller bottom end, better cymbals, more impactful drums, and a warmer sound with a touch of sweetness on the vocals. It is less analytical, and doesn’t fatigue. I find the sound a bit more engaging from the ma750. I think that the ma750 will appeal to people who state they are searching for a warm analogue sound. It delivers that in spades. I give the the ma750 a solid 4.25.
 
Buy both headphones, or buy whichever flavour sounds more to your liking. Also, buy Black Star. I think it is Bowie’s best album since Berlin. It borrows some sound from his Berlin years, infuses some soul from the 80s and more modern production techniques. It is a remarkable stylistic synthesis of the career of a remarkable man. It is as fitting a eulogy as anyone could have given.