Select Comparisons
All comparisons were completed using a mix of the 64 Audio U4s, Campfire Audio’s Andromeda 2020, and the JH Audio Contour XO for our IEM selection. For headphones, we used the Meze Audio Liric and Audeze’s MM-500.
FiiO M17
$1799
The FiiO M17 is the company’s flagship digital audio player. Launched at the tail-end of 2021 and reviewed by us in January 2022 we gave it some high praise indeed. You can read our full review of the M17 here.
Technical
Both DAPs use an ES9038PRO DAC implementation but like the Q7, the M15S uses a single chipset as opposed to the dual setup inside the M17.
Decoding, however, is much the same with both DAPs capable of up to DSD256 and PCM 32BIT/386kHz naively with both rising to 768kHz and DSD512 on USB Audio out. MQA on both is limited to 8X unfolding capability with additional Roon Ready capability.
They also use the same BT 5.0 chipset, the QCC5124 with similar codec handling including transmitting and receiving up to LDAC with additional aptX LL and Adaptive receiving capability.
Despite sharing the same dual-power philosophy the THX 788+ equipped M17 is by far the more powerful of the two headphone amplification circuits. You get up to 1.5W balanced in battery mode on the M17 compared to the maximum of 990mW in the smaller M15S.
Slap on DC power mode on the M17 and that doubles to 3W whereas the equivalent desktop mode on the M15S will give you 1.2W balanced max on a 32Ω load. Both are great numbers bringing a wide range of headphones into play but the M17 will handle a lot more power-hungry headphones and is a true desktop replacement.
Processing-wise, there is not a huge difference. Both use a Snapdragon 660 Soc with 4GB of RAM under a layer of Android 10 with a stripped-down alternative FiiO Pure mode.
Our AnTuTu scores for both were very close so you won’t see much of a difference in terms of aesthetics and speed save for the different screen sizing and better 1080p resolution on the M17.
Design
Ah, no question which is the more portable unit. The M15S is both lighter and smaller than the M17 and is by far the more portable device with single-handed use possible.
This is Bauhaus versus mecha in aesthetics also and I do have a feeling the minimalist design of the M15S will appeal to older users compared to the aggressive multi-LED and edged design of the M17.
This is also 5.9″ 1080p versus 5.5″ 720p for screen real estate so the M17 will be easier to read and navigate for larger media file collections.
I/O on the M17 is the more complete of the two with more USB ports, a separate DC power connection, a dedicated coaxial I/O, and a 6.35mm output on the M17.
The M15S does quite well with both balanced 4.4mm and 2.5mm as well as 3.5mm SE for PO but its single USB-C means you cannot go into desktop mode and connect something like an external drive to the port same time.
Battery life is similar though at just a little over 10 hours SE and 8 hours balanced for the M17 compared to 10.5 and 9 hours for the M15S. The M15S is also an hour faster in charging from 0 to 100% compared to the M17.
Both do come with their respective stands, the DK3 for the M17 and the DK3S for the M15S. They operate in a similar fashion the only difference being size with the DK3S the smaller of the two stands for the smaller DAP.
Performance
I thought I should preface the color commentary with a more neutral observation regarding the differences in their low gain volume control using the Andromeda 2020.
Although both have really good channel balancing the THX amplified M17 is more refined in its incremental increases from zero upwards whereas the M15S feels muted at 0 and then in with a higher level of volume right away on 1.
From there the M15S volume control is a little more aggressive in its incremental gains so I would advise switching to the digital control for sensitive IEMs on that basis. Otherwise, the background noise is very low on both DAPs using the Andromeda 2020.
Performance-wise, the M17 is technically superior but I have a feeling that some might prefer the general tonal coloration of the M15S. It sounds smoother and a little less edgy in the upper mids and lower treble also.
That does seem to have come at the cost of headroom and treble extension with the M17 sounding the taller and roomier of the two DAPs.
Certainly, the dynamic range and resolution on the M17 are more convincing and it will fill out the presentation of planar headphones such as MM-500 a bit more.
It sounds more holographic, note texture has more detail and instrumental separation is more noticeable. Of the two, it is the more immersive whereas the M15S is comparatively centered or just ahead of you in terms of imaging with the Andromeda 2020.
However, the M17 still has that little harmonic battle in the upper mids and treble. As a result, it can sound a little edgier and sharper with our chosen IEMs. So, if tonal smoothness is your top priority the M15S’s slightly softer tonal quality in higher-pitching vocals and instruments might be more persuasive.
HiBy RS6
$1399
The HiBy RS6 is a ‘mid-fi’ R-2R DAP and the first by the company to feature its Darwin architecture in late 2021. We also reviewed it at the end of that year and gave it our Editor’s Choice in our Top Gear Awards for 2021. You can read our full review of the RS6 here.
Technical
The RS6 takes a very different approach with its overarching Darwin Architecture and at its heart a discrete-engineered 24BIT resistor ladder network or R-2R DAC implementation as opposed to the M15S’s delta-sigma single ES9038PRO design.
Decoding, however, is similar for DSD with both DAPs offering up to DSD256. Where the RS6 stretches its legs a bit is PCM at 32BIT/768kHz as opposed to 384kHz native on the M15S. The RS6 is also able to unfold MQA up to 16X as opposed to the M15S’s 8X capability.
Both DAPs are equipped with two-way transmitting and receiving BT5.0 capability. That means a maximum of LDAC 24BIT/96kHz in both directions and ACC for iOS. You can also access wireless lossless transmission with a 2.4G/5G WiFi dual antenna inside both devices.
The M15S is the more powerful of the two DAPs for headphone output at 990mW battery mode balanced and up to 1.2W in desktop mode. The RS6 has no alternative boosting mode such as the Turbo mode found on the RS8 so it drops to 180mW@32Ω SE and 690mW@32Ω balanced and will struggle more than the M15S with more demanding headphones.
Both DAPs offer balanced and 3.5mm line-out and 4V and 2V though I do prefer the dedicated outputs of the RS6 compared to the switching PO/LO sockets of the M15S.
The M15S has a more modern Android 10 OS compared to the RS6’s older Android 9. However, both OS are supported by the same Snapdragon 660 CPU with 4GB of RAM so their AnTuTu scores are quite similar. Neither is discernably slower than the other.
If anything, the RS6 Darwin Architecture and the various DSP management options are the more sophisticated of the two DAPs in terms of interactive sound-shaping features.
Design
The RS6 is the smaller and more portable DAP with a very sleek low profile machined copper, (or grey), finish. Of the two DAPs, it is slimmer and more pocketable in terms of dimensions with the M15S roughly 20% taller and a little wider also.
Despite the smaller size, the RS6 is quite heavy due to the materials being used in its housing at 335g and very close to the M15S 345g official weight. They both have a very similar feel in the hand.
Some might prefer the smaller size of the RS6 and its higher-quality 1080P 5″ panel, while others might prefer the bigger 5.5″ panel on the M15S for media management despite it dropping down to a 720p resolution. A question of preference here though I must say Android 10 does a better job theming on dark mode compared to Android 9.
For I/O I would give an edge to the M15S in certain matters such as its dual power and desktop mode capability from its single USB-C port though I do prefer the RS6’s separated SE and balanced line-out port arrangement. Both have similar onboard memory capacity at 64Gb with a single external TF card slot for microSD cards and USB-OTG capability.
Battery life between the M15S and the RS6 is also quite similar at 8 hours balanced and 10 hours SE for the RS6 and 9 hours and 10.5 hours for the M15S. The key advantage for the M15S is the ability to switch off the battery to conserve its lifespan when its desktop mode is activated.
Performance
The RS6 creates a more emotive sound, one with a stronger fundamental and richer more saturated vocal performances, especially in NOS mode. The M15S is not clinical sounding but does sound more neutral in both imaging and coloration compared to the RS6.
The M15S does cast an airier soundstage, at least with the 64 Audio U4s and Andromeda 2020, our two tested monitors. Instruments have a slightly drier tone, are more controlled on the mid-bass bloom, and with a shorter amount of decay which helps emphasize the spacing and increased the perceived speed and articulation.
That airiness is complimented by a stronger treble presence though the M15S harmonic balance in the highs is actually very good, with nothing too sharp or forward with our pairings helping to create a neutral to natural tone in the mids.
The RS6 is lusher in its mids presentation and can sound comparatively congested though it does very well at pushing out its vocal presence and mid-bass bloom which are two big contributing factors in that weightier and denser tonal coloration.
I would certainly pick the RS6 for the 65 Audio U4s though as its bass and vocal richness do really well with that dynamic driver and BA mids which you do not want to sound thin or light in their delivery.
However, for the Andromeda 2020 pairing, I might err with the M15S just for the increased clarity and better balance in its precise tuning. It depends really on your preferences because they sound quite different to my ear they are almost complementary.
iBasso DX240
$949
The iBasso DX240 was launched in early 2022 and is a refresh of the previous DX220 with a new set of amplification cards. It is priced very close to the M15S. You can read our full review of the DX240 here.
Technical
Both have a very similar single ES9038PRO DAC chipset implementation as well as a Snapdragon 660 SoC backed up by 4GB of RAM. They also make use of FPGA and dual NDK Femtosecond Crystal Oscillators for digital signal processing and jitter control before conversion via the DAC to analog.
Decoding levels do differ with the M15S limited to DSD256 and 32BIT/384kHz natively and the DX240 able to go further at DSD512 and PCM 32BIT/768kHz. MQA is also set to 16X on the DX240 as opposed to the lower 8X rating on the M15S.
Both are WiFi dual 2.4G/5G and BT 5.0 equipped with up to 24BIT/96kHz receiving and transmitting capability as well as lossless transmission via 3rd party streaming, Airplay, or DLNA.
Amplification is where they really differ though with the DX240 compatible with the older DX220/200’s wide range of interchangeable AMP cards and the M15S with a fixed amplification output.
What the DX240 lacks though is the M15S’s capability to bypass the battery altogether and really ramp up the power via its desktop mode. You get more flavor and more variety of amplification with the DX240 but you get more power from the M15S PO output period.
Since we are keeping this price sensitive we will be comparing the stock DX240 AMP1 MKIII card. This has a maximum rated balanced output of 878mW into a 32Ω load and 281mW@32Ω which is very competitive to the M15S’s battery mode maximum of 990mW balanced and but less so against the 390mW SE rating.
It’s the desktop mode though that sets the M15S apart for pure numbers at 1.2W balanced and 580mW SE into a 32Ω load. The closest the DX240 can go is with AMP8 MKII at 980mW into the same load.
Design
The DX240 is the most portable of the compared DAPs. The Dx240 is smaller, much smaller than the M15S, and also a fair bit lighter at 205g compared to 345g. The form factor is also more ergonomic in the hand with a curved back that rests beautifully in your palm making it a very comfortable user experience physically.
The M15S screen is bigger at 5.5″ compared to 5″ but it is a lower resolution at 720p compared to 1080p as well as having a thicker bezel. iBasso has always done well with borderless designs and the DX240 is no exception though I feel some will prefer the more screen real estate offered by the M15S.
The DX240 physical control set is a bit more simplistic though with a fairly low-profile potentiometer that is not quite as easy to work with as the M15S and a reduced set of buttons that cover power and playback. It has no lock capability or multifunction button features. You also cannot switch between digital and analog volume control on the DX240.
The I/O is also a bit more limited on the DX240. The stock AMP1 III card lacks a 4.4mm output and a balanced line-out with only a shared 3.5mm lineout. Both offer digital connectivity through USB-C and coaxial ports and 64GB of onboard memory with a single microSD slot.
With the recent firmware update, the DX240 now uses a dual boot Mango and Android 11 giving it a small edge over the M15S’s Android 10 and Pure Mode layer, especially with its PMEQ suite inside its Mango app.
For AnTuTu, the scores are similar at 173k for the DX240 and 178k for the M15S so you won’t see much in the way of speed differences.
Performance
For this comparison, I used the Contour XO pairing which is a clean and lively-sounding IEM though you can exaggerate the bass with the JH Audio bass booster module. I did just that and pushed it to the maximum just to see how each DAP managed it.
A good summary of the differences between these two is similar to moving from a quality copper cable, (M15S) to a quality silver cable, (DX240).
With the DX240 it was the more controlled sounding and kept the bass reasonably tight. However, the additional warmth from the bass module pushed down a little on the more neutral imaging of the midrange vocals.
The Contour XO is already quite neutral in the mids so perhaps not the best pairing overall though the DX240’s stronger treble sparkle did help to give higher pitching notes more headroom and energy compared to the M15s.
The M15s did much better handling the full-on lows of the Contour XO on the maximum bass setting. It kept vocals to the fore sounding richer and more composed. However, the M15S does not have the same level of upper treble extension so it’s not as airy or as tall as the DX240.
That means your ear is more drawn to the smoother richer timbre of the bass and mids whereas the DX240 switches it upwards teasing out cleaner mids and highs.
I have to note this is nuanced rather than overt, the DX240 is still quite balanced in its tone rather than bright. It is just not quite as rounded with more of an ethereal quality in the mids and highs. It does image a bit better for upper mids and highs whereas the M15S delivers a bit more on low-end weight and mids timbral density.
Our Verdict
The FiiO M15S is an excellent mid-tier DAP that covers both the IEM and headphone bases very nicely with very good output power and a much improved tonal balance from the original M15.
And I think that is what I want to emphasize the most, the tonal balance, particularly for owners of the original and headphone users.
There is a certain smoothness and improved weight to its sound quality that I much prefer over the older tuning. It gives also gives those thinking about the M17 a second option that may not be quite as technically good or as powerful but might prove preferable for a lot of pairings with its balanced neutral-to-natural tone.
The second harmonic distortion option in particular impressed me with how it handled bright mixes and vocal sibilance.
Of course, Android 10 is not going to break any new ground and may in fact draw from criticism. However, I prefer instead to look at what FiiO has added to the M15S feature set, and pretty much everything is there that you need including the desktop fan when you really want to drive it hard.
Coming in at a third of the price of the original, the M15S might well prove a worthy alternative for those complaining about the lack of power from competing DAPs in the same tier.
FiiO M15S Technical Specifications
- ES9038Pro DAC
- Snapdragon 660 SoC
- 5.5” Display Screen
- Android 10 OS
- 4GB RAM
- 64GB Internal Storage
- Qualcomm QCC5124 Bluetooth Chipset
- Two-Way Bluetooth Connectivity
- Two-Way USB 3.0 Connectivity
- Integrated RGB Indicator in Volume Wheel
- Balanced Line-Out Support
- Power Output up to 1.2W per channel
- Apple Music, Roon Ready
- Dual Power Supply Mode
- High-Power Headphone Output Mode
- Desktop Mode Support
- Disable Battery Charging While Using USB DAC Support
- Supports FiiO DK3S Cooling Stand
