Hello Everyone,
This is a review and detailed measurements of the Fiio DM15 CD Player and Transport:
View attachment 517425
Note that I did not remove the blue protection cover for this picture.
Fiio DM15 - Presentation
Fiio themselves present this new DM15 as "slimmed down version of the DM13" which I previously reviewed
here. They also talk about an
R2R conversion design (I let you look this up with your favorite AI) and that this DM15 "
represents a breakthrough (...) surpassing the competition". To be fair, they only mention two facts related to its smaller footprint and stronger feature set, not pure performances that we are addicted to, at least on ASR.
I guess it is enough for me to point you to the
official website where you can grasp all the features of this new little device.
On the back of the Fiio DM15, we get additional outputs, balanced and unbalanced via 4.4mm and 3.5mm jacks, the latter serving as SPDIF out (digital and coax):
View attachment 517430
You can also see the "ESP" button related to more resistance to shocks, but that did not influence my measurements, and Fiio state that "
Enabling the ESP function improves playback stability, but (...) does not significantly enhance the disc reading performance".
There is a "Desktop Mode" (D-MODE), where the Fiio DM15 can be used a DAC with a Computer.
User experience
The time to read the TOC is quite long (up to 22sec) but that is because it recalls the last position of reading. The drive is quite fast to skip one or multiple tracks though, as well as FFW/REW, which I like.
What I did not like are the very small buttons and the associated symbols that are nearly impossible to read to me, unless I benefit from bright light. This is a clear step down from the DM13.
The display is equally way too small for me, especially considering all of what it intends to show. But I guess this is ok as a Desktop device.
As Fiio says on their website, I could run the unit for 7 hours straight on batteries (for my testing) before I had to recharge it, which is a very good performance, I think.
Fiio DM15 - Measurement (Analog out)
All measurements performed with an E1DA Cosmos ADCiso (grade 0), associated to the Cosmos Scaler (100kohms from unbalanced input) for analog outputs, and a Motu UltraLite Mk5 for digital.
Similar to what I did with the
DM13, I used a 4.4mm to 3.5mm balanced cable from Fiio, to perform the below measurements.
The Fiio DM15 outputs a very high 7.8Vrsm from balanced outputs (I did not test unbalanced). There was a slight channel imbalance of 0.11dB which is decent, and actually better than the DM13. The balanced outputs are inverting.
For the following test, I set the output to near 4Vrms, so to keep some sort of standard, but I must mention that performances were identical at full output, and 2Vrms too, by the way. All measurements were performed with the Fiio running on batteries, and I checked they were the same when externally powered.
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As usual, let's start with my standard 999.91Hz sine @0dBFS (without dither) from the
Test CD (XLR out):
View attachment 517432
Ouch, this is bad. Only
11.3 bits of real resolution. There is a higher than usual noise floor (11dB higher than best in class), but what kills the SINAD (that is less than 70dB) is the harmonic distortion. In all the CD players I reviewed, I've never seen that bad. This very high distortion is made primarily of odd harmonics, spreading far away from the fundamental (not good).
As I'm used to do, let's check is maybe things improve at -6dBFS:
View attachment 517437
Unfortunately not, performances did not degrade though. But with only 11.2bits of resolution, there is no reason to see degradation at lower output levels...
Note the 999.87Hz sine seen by the interface (instead of 999.91Hz). This is weird because I've seen the pitch of the DM15 varying from time to time. I have no explanation for that, this is a first for me.
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I usually show potential power supply leakages as below:
View attachment 517439
It would look nice if the noise floor was not so high...
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Next is the bandwidth:
View attachment 517443
This is good (flat) but there is sharp cut at 19kHz and the attenuation is -1.5dB at 20kHz. We can also see the channel imbalance a little above 0.1dB.
Since there is an EQ with preset parameters, I thought it would be nice to show how they impact the bandwidth:
View attachment 517444
The presets are "JAZZ", "ROCK", "POP", "DANCE", "CLASSIC" and "HIP-HOP". In the above graph, the black line is with the EQ set to "OFF". I let you look at the legend to see who's who. Note that the "POP" setting plays a good -3dB minimum below the EQ OFF.
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Let's have a look at the efficiency of the digital filter:
View attachment 517453
Well, we get only -60dB attenuation, which is poor. The dual tones of the IMD AES test are poorly attenuated, and they duplicate as a consequence beyond 20kHz.
You can also see the IMD components (side bands of the dual tones) at an unusual high level (-70dBr) and duplicating too below and beyond 20kHz (not good).
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Let's have a look at the multitone test that a lot of you like very much, and guess what:
View attachment 517454
This view is as bad as it gets, and that is 30dB more distortion than best in class. That said, we still get a surprisingly 13bits of distortion free range, which is better than with a single tone.
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Oh yes, the jitter test:
View attachment 517456
Red shows what we should get, and blue shows the result of the Fiio. This is unusually bad for a modern device.
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Started with the
Teac VRDS-20 review, and on your request + support to get it done (more
here), I'm adding now an "intersample-overs" test which intends to identify the behavior of the digital filtering and DAC when it come to process near clipping signals. Because of the oversampling, there might be interpolated data that go above 0dBFS and would saturate (clip) the DAC and therefore the output. And this effect shows through distorsion (THD+N measurement up to 96kHz):
The Fiio has a good resistance to ISO up to 2dB, the results being limited by the distortion of its DAC. At +3dB, it clips, as many others.
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Let's continue with the good old 3DC measurement that Stereophile was often using as a proof of low noise DAC. It is from an
undithered 997Hz sine at -90.31dBFS. With 16bits, the signal should appear (on a scope) as the 3DC levels of the smallest
symmetrical sign magnitude digital signal:
View attachment 517460
Unfortunately, this is not what we get. There is an absence of symmetry meaning that this CD player has lost its linearity way before this not so low level (for a modern DAC). There is also a bit of noise too, but less than when it plays near or full scale test tones. This means that this DAC is not at ease with high or low level signals and suffers multiples linearity issues.
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Other measurements (not shown):
- IMD AES-17 DFD "Analog" (18kHz & 20kHz 1:1) : -67dB
- IMD AES-17 DFD "Digital" (17'987Hz & 19'997Hz 1:1) : -63.4dB
- IMD AES-17 MD (41Hz & 7993Hz 4:1): -71.5dB
- IMD DIN (250Hz & 8kHz 4:1) : -56.1dB
- IMD CCIF (19kHz & 20kHz 1:1) : -63.2dB
- IMD SMPTE (60Hz & 7kHz 1:4) : -56.2dB
- IMD TDFD Bass (41Hz & 89Hz 1:1) : -76.5dB
- IMD TDFD (13'58Hz & 19841Hz 1:1) : -74.5dB
- Dynamic Range : 95.2dB (without dither @-60dBFS)
- Crosstalk: 100Hz (-133dBr), 1kHz (-116dBr), 10kHz (-97dBr)
- Pitch Error : 19'995.73Hz (19'997Hz requested) ie -63.5ppm
- Gapless playback : Yes
The IMD scores are the worst I measured from a CD Player.
The Dynamic range is surprisingly good (-95.2dB) when measured at -60dBFS, but it degrades at higher levels.
Crosstalk is very good.
Pitch error is an usually high -63.5ppm for a modern CD player. On top of that, I saw it increase from time to time. For a few seconds, it increases regularly and then goes back to that -63.5ppm deviation. Weird.
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Last and not least, I like to run a THD vs Frequency sweep at -12dBFS as it shows how the conversion has evolved over time. This is interesting in the context of an R2R DAC, which is an old type of conversion. So let's see:
View attachment 517469
Ouch (again). I overlaid the results of the best in class SMSL PL200 for comparison. The graph speaks by itself. The distortion of the Fiio DAC limits its resolution to less than 12bits.
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As I did with the
Sony CDP-597, I add a "
max DAC resolution" measurement test. It is performed from a 999.91Hz sine @-12dBFS with shape dither (from Audacity). I restrict the THD+N span to 20Hz - 6kHz in REW not to account for the noise of the shape dither beyond 6kHz. I take the calculated ENOB and simply add 2bits to it (due to the -12dB attenuation, as 1bits=6dB). The potential maximum, when calculated from the digital WAV file, is 18.7bits under this test. A "transparent" DAC should achieve 18.7bits, ie 100% in this test.
Here are the results compared to others:
Unfortunately, and one more time, the Fiio sets a precedent of mediocrity. Its real resolution is below the very fist DAC from Philips which was processing only 14bits...
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On repeating requests from the community, I now perform a "de-emphasis test" to verify that this flag is detected and the compliance with the expected de-emphasis curve.
The Fiio does not apply de-emphasis when required, unfortunately.
Fiio DM15 - Testing the drive
What would be good measurements if the drive would not properly read a slightly scratched CD, or one that was created at the limits of the norm? The below tests reply to these questions.
Here are the results:
| Test type | Technical test | Results |
| Variation of linear cutting velocity | From 1.20m/s to 1.40m/s | Pass |
| Variation of track pitch | From 1.5µm to 1.7µm | Pass |
| Combined variations of track pitch and velocity | From 1.20m/s & 1.5µm to 1.40m/s & 1.7µm | Pass |
| HF detection (asymmetry pitch/flat ratio) | Variation from 2% to 18% | Pass |
| Dropouts resistance | From 0.05mm (0.038ms) to 4mm (3.080ms) | 2.4mm |
| Combined dropouts and smallest pitch | From 1.5µm & 1mm to 1.5µm & 2.4mm | 2mm |
| Successive dropouts | From 2x0.1mm to 2x3mm | 1.5mm |
The above are very good results, better than most old legendary drives such as the Sony KSS serie. That said, the
DM13 did even better than that.
Fiio DM15 - Measurements (Optical Out)
If the Fiio does not excel on its analog outputs, let's try the digital ones. It tested the Optical Output using a 3.5mm mini Toslink cable.
Let's start with the regular 999.91Hz test tone @0dBFS:
View attachment 517658
I'm not really surprised to see that the digital output is modified, meaning that the processing performed in digital domain, is the one that goes out to SPDIF. Note that the Fiio plays 2dB lower than wanted, which would explain the 2dB resistance to intersample overs that I reported.
Note also the pitch error, this is 999.85Hz instead of 999,91Hz. Seeing that error here (it's a first, one more time) means the clock that drives the DSP of the Fiio is unprecised.
And like I said before, it varies to go back to normal, look:
View attachment 517659
This is a weird behavior, because from time to time, I see it vary and then stay fixed from some time at the wrong 999.84Hz or the required 999.91Hz. This will not impact the listening experience, but I've never seen such an issue.
Let's try the 3DC test to check if we get our wanted symmetry in digital domain:
View attachment 517660
Err, no we don't. Checking closer, I see that we loose linearity as soon as at -70dBFS, which should be a -72dBFS since the signal is attenuated by 2dB, but no, it is more than 1dB off:
View attachment 517663
Also, note the distortion that is constant and so is much higher now relative to this small signal. There's no notion of high resolution here.
With my other reviews, I use the ISO test file, test tone 5512.50Hz @0dBFS with Phase shift of 67.5°, and with dither), to compare with the source WAV file if the output is bit perfect. Ok, we already know it's not the case here, but let me show you anyways:
View attachment 517664
Of course, the level is 2dB below expected, we get again that pitch error and the unwanted distortion, but you can also see that the SNR degraded by 2dB, which is due of course to the 2dB attenuation that the Fiio applies in digital domain.
By the way, the EQ is active with digital output too, no surprise:
View attachment 517671
I don't know the use case for that, but I guess Fiio did not bother creating a separate patch for the digital output and simply use the same output for whatever DSP they use direct to the SPIDF output.
All of that is unwanted and sad, if you ask me.
Fiio DM15 - Measurements (as a DAC)
Considering the bad results I got as a CD Player, and since it is its primary use case, I did not bother to test it as a DAC, but I might take the time in the future.
Conclusion
What can I say? This CD Player is by far the worst I tested. Besides a more than decent resistance to scratched CDs, I can't see anything good with this one.
And of course I was interested to know if I would hear something. And as a matter of facts, when I test if a CD player is gapless, I always use the same CD from Pink Floyd - The Dark Side Of The Moon, one of the early versions.
And for the first time, I had to stop listening to it, the sound was fatiguing to my hears.
EDIT: It was that my early edition that requires de-emphasis, and that explains harsh high frequencies I heard, since the Fiio does not apply de-emphasis per my measurements. With the Live « Delicate Sound of Thunder », I could not spot obvious faults, and that is interesting.
Anyways, all of this is unfortunate, but I can't recommend this CD Player. Maybe mine has an issue, I don't know. And, to be honest, when I started measuring it, I thought I had a problem with my setup, and so I quickly switched to an old Teac VRDS 25x. And so no, no issue with my measurement setup, it was indeed the Fiio being so bad.
Of course, I tried to set the Fiio and use it in the various options it offers (front and back outputs, more or less output power, D-MODE / ESP ON/OFF, powered or on batteries, updating the firmware, ...) and I got the same bad results.
I am open to feedback, including from the manufacturer. I'll keep the Fiio not far from my bench, so if there's anything I can try, on top of what I've already done, please feel free to suggest.
I hope you enjoyed this review and I wish you a nice weekend!
Flo
www.fiio.com
).
