INTRO: This is another article in a series of inexpensive USB DAC reviews including the Turtle Beach Micro II and Syba C-Media CM119. Like both of those DACs, it uses yet a different version of an all-in-one C-Media chip (the CM108). So how does FiiO’s least expensive USB DAC measure up against it’s peers?
FiiO D5 USB DECODER: The D5 is a bit different than the other two C-Media DACs. It doesn’t plug directly into the USP port but instead has a short detachable USB cable using a mini USB plug allowing use of other cables. And, true to their tradition, FiiO manages to include several extra features not found elsewhere at this low price. The build quality is impressive using a full metal enclosure instead of plastic. FiiO also includes volume up/down buttons and mute buttons for the output and microphone. There’s an LED that shows it’s been acknowledged by the operating system and another for the Mic Mute. Plus you get two microphone jacks instead of one, a headphone out, a separate line out, and a coaxial digital output. When you consider the D5 has the same $25 street price as the Turtle Beach Micro II, FiiO gives you a lot more features.
FiiO D5 VOLUME CONTROL: The volume control isn’t a “local” volume control in the analog domain after the DAC (as in say the NuForce uDAC-2). Instead it’s really just a remote control for your PC’s volume control. Pressing the up and down buttons on the D5 changes the volume settings for the D5 in Windows (I didn’t test OS X or Linux). So it does not help preserve full 16 bit resolution at lower volume settings. Using the controls on the D5 is no different than using your PC’s volume control which causes a reduction of bit resolution at anything but full volume. Still the volume buttons could be useful, especially if you use a long USB cable and the D5 is located away from the PC or allowing volume adjustment without turning the screen on or logging onto a “locked” PC.
WINDOWS INSTALLATION: The D5 installed smoothly in both XP and Windows 7 without needing any drivers. Windows reported it, interestingly, as a “C-Media USB Headphone Set”. The only sample rates and bit depths available are 16/44 and 16/48 as shown to the right in Windows 7 (click for larger).
SUBJECTIVE SOUND QUALITY: There was moderate hiss and noise with my Ultimate Ears IEMs and it was noticeably worse than the Turtle Beach Micro II and about the same as the Syba CM119. The sound quality seemed similar to the Micro II with its odd dynamic range control turned off but the D5 has more output and seemed to sound a bit better driving 16 ohm headphones than the Syba CM119. A blind test would be required to know for sure, but I’m fairly sure the D5, like the CM119 and Micro II, has some audible flaws.
MEASUREMENT SUMMARY: The overall results were not very impressive and generally similar to the Turtle beach Micro II and Syba CM119 which use two other chips from C-Media. This doesn’t speak well for C-Media based products when three different DACs, using three different C-Media chips, all have significant problems. There are some differences between the three. The D5 has the highest line and headphone output voltage and the lowest output impedance but the Micro II and CM119 have better frequency response into a line level load. The CM119 does especially poorly with lower impedance headphones. Here are the results compared to the $12 CM119, $25 Turtle Beach Micro II, and the $30 Behringer UCA202. The scores are “A” (excellent) through “F” (unacceptable):
|Measurement||FiiO D5||CM119||UCA202||TB Micro II|
|Freq. Resp. 10K||+/- 1.5 dB C||+/- 1.0 dB B||+/- 0.1 dB A||+/- 1.0 dB B|
|Freq. Resp. 33 ohms||+/- 1.5 dB C||+/- 6 dB F||N/A||+/- 1.8 dB C|
|HP Output Imp||0.72 Ohms A||5.9 Ohms C||47 Ohms F||0.95 ohms A|
|Max Output 10K||1.5 Vrms B||0.95 Vrms C||1.12 Vrms B||1.34 Vrms B|
|Max Output 33 Ohms||1.4 Vrms B||0.68 Vrms C||N/A||1.26 V B|
|Max Power 32 Ohms||61 mW B||14 mW C||N/A||50 mW B|
|THD+N 0 dBFS 10K||0.24% C||0.035% B||0.008% A||0.14% C|
|THD+N 100hz 10K||0.08% C||0.035% B||0.007% A||0.025% B|
|THD+N 1Khz 10K||0.08% C||0.035% B||0.007% A||0.02% B|
|THD+N 1Khz 33ohms||0.08% C||0.095% C||N/A||0.12% D|
|THD+N 10Khz 10K||0.04% B||0.090% C||0.009% A||0.11% C|
|IMD CCIF 10K/33||011% D||0.028% D||0.005% A||0.028% D|
|IMD SMPTE 10K||0.80% D||0.012% B||0.002% A||0.02% B|
|Noise A-Wtd dBu||-90.0 C||-89.0 C||-88.8 C||-93.8 B|
|-90 dBFS Linearity||0.7 dB A||0.9 dB A||3.8 dB C||0.8 dB A|
|USB Jitter Jtest||Poor D||Poor D||Very Good B||Poor D|
- It’s cheap
- Nice build quality
- Volume & Mute controls
- Coaxial digital output
- Likely worse than many built-in (motherboard) sound outputs
- Significant low frequency roll off from headphone and line outputs
- High overall distortion, especially at low and high frequencies
- Relatively noisy
- Relatively high jitter
BOTTOM LINE: The extra features, especially the Mic Mute button, make the D5 especially well suited for things like Skype and web chat. But, otherwise, it’s external features and impressive build quality are only “skin deep”. What’s inside is yet another poorly performing C-Media chip. Of the three C-Media based USB DACs I’ve tested this one has the most features and highest output but is slightly less laptop friendly for portable use. Each of the C-Media DACs I’ve tested has a few unique relatively strengths and weaknesses. See the Measurement Summary above and Tech Section below for more details. As a secondary audio source for non-critical applications, or perhaps as a primary source for voice chat, Skype, etc, the D5 is a reasonable choice. For high quality audio, however, the Behringer UCA202’s line outputs perform far better for about the same price. And, as documented in my next two reviews, there are some better choices for portable USB “thumb DACs” for only slightly more money.
TECH STUFF: Based on information from the web, the D5 appears to use the C-Media CM108. Like the CM119 and CM102, used in the Syba and Micro-II respectively, it’s a fully integrated single chip that does everything necessary for a USB headphone DAC with a few extras thrown in. The volume control is simply another USB endpoint to allow remote control of the PC operating system volume and mute control. This is natively supported in Windows XP, Vista and Win 7 with no special drivers.
HEADPHONE TESTS: As with the other recent DAC tests, I used a 33 ohm load to represent typical portable headphones in the 16 – 80 ohm range. I also spot checked a few results into other impedances from 15 to 600 ohms. These tests were made from the headphone jack.
LINE OUT TESTS: I used 10K which is the typical input impedance of many headphone amps, such as the O2, and powered speakers. Performance into 22k or 50K loads will be very similar. I ran a few tests at 100K. I used the line out jack for these tests.
FREQUENCY RESPONSE: The other two C-Media based DAC’s had relatively flat low frequency response into 10K but not the D5. From either output it rolls off the bass so it’s down about 3 dB at 20 hz. This implies an undersized coupling capacitor that’s “upstream” of the line out buffer and headphone amp. Some might argue this amount of roll off is inaudible as the ear is less sensitive at very low frequencies, but it’s still disappointing. It means significant phase shift much higher in the audio spectrum and with headphones and recordings that go down to 20hz, you just might hear the loss of deep bass. The high frequency performance suffered the same poor filtering, ripple, and early roll off as the other two C-media DACs. Again, this will create significant phase shift in the audio range. Besides the line output roll off, the other big difference is the 33 ohm headphone load didn’t change the low frequency roll off. So apparently it’s a direct coupled headphone output. The second graph shows the Micro II for comparison. Note the Micro II is flat to below 10 hz into 10K and even does a bit better into 33 ohms:
THD+N vs OUTPUT: The D5 has slightly higher maximum levels than the Micro II but somewhat more distortion into 10K. The headphone jack into 33 ohms managed a relatively impressive (for this class of product) 1.4 Vrms. Into 15 ohms that dropped to 1 Vrms before hitting 1 % THD and into higher impedances it would hit 1.5Vrms. Power levels into 16, 32, 80, 150, 300 and 600 ohms are 63 mW, 61 mW, 28 mW, 7.0 mW and 3.7 mW respectively. While the headphone jack has more output than average, the distortion from both jacks is disappointingly high—generally around or well above the 0.05% goal. The second graph shows the Micro II for comparison (the trace colors are swapped and horizontal scales different):
100 hz 0 dBFS THD+N & OUTPUT IMPEDANCE: The first graph shows the line output can mange the same 1.5 Vrms as the headphone output into high impedance loads. At 0 dBFS the distortion was 0.24% which isn’t great but I’ve seen worse. At least the worst of it is the 2nd harmonic. In the second graph the D5 headphone output is over 1% THD at 1.04 Vrms. Removing the load increases the output to 1.09 Vrms for an output impedance of 0.72 ohms. This is fairly impressive and is another sign there are no output capacitors. The third graph shows the Micro II for comparison:
THD+N vs FREQUENCY: The D5 did especially poorly on this test at 0 dBu (775 mV). There’s little difference between the line out jack into 10K and the headphone output into 33 ohms. Both are around 0.06% to 0.10% over most of the audio spectrum and much worse below 100 hz and above 14 khz. This is not what I would call a “clean” DAC. As can be seen by the second graph of the Micro II, it’s significantly worse than even similar C-Media peers. The third graph shows the $30 Behringer UCA202 which has about twenty times less distortion (0.007%) from its line output jacks. An extra $5 buys much better performance despite the UCA202 being a much older design:
SMPTE IMD 33 OHMS: Even at only around 400 mV the dScope’s calculated SMPTE value of nearly 0.8% was pretty awful. Some of the IMD products clustered next to the 7 Khz signal are well above the desired –80 dB, as is the THD from the 60hz signal. The rest of the spectrum isn’t so bad. While the calculated value is higher, the spectrum is very similar to the Micro-II:
CCIF IMD MICRO II 44 Khz 33 Ohms: The D5 wasn’t quite as awful as the Micro II on this test but it was still fairly similar with lots of distortion products above –80 dB. This is rather poor performance:
CCIF IMD MICRO II 44 Khz 10K: Into 10K the CCIF IMD is only slightly better than into 33 ohms above. This is similarly bad to the CM119 and Micro II. The 48 Khz sampling rate was also similar to the Micro II. The second graph shows the Behringer UCA202 for comparison and more how it should look:
NOISE & LINEARITY: The weighted noise of the D5 was about 5 dB worse than the Micro II and very similar to the Syba CM119. This is marginal noise performance but is still acceptable for some applications and similar to the UCA202. The linearity was very similar to the Micro II and CM119 with less than 1 dB of error. The second graph shows the Micro II for comparison:
JITTER: Here’s the spectrum from the dScope’s J-Test for jitter. The result shows a lot of low frequency jitter (“spread” in the 11025 hz signal) almost identical to the Syba CM119. It’s much worse than average even compared to the $30 UCA202. At least the frequency accuracy (clock accuracy) is very good as shown by the frequency reading on the left. The second graph shows the UCA202 for comparison. Note how the “spread” is confined to below –118 dB on the UCA202 but reaches up beyond –70 dB with the D5:
TECH SUMMARY: Having reviewed the Turtle Beach Micro II, Syba CM119, and now the FiiO D5, it’s fairly obvious three different C-Media USB DAC chips all suffer some of the same major weaknesses. They include:
- Poor High Frequency and IMD Distortion
- Poor Jitter Performance
- Poor High Frequency Response
- Poor High Frequency Filtering (frequency response ripple in the audio band)
- Excessive Phase Shift In The Audio Band
- Excessive Low Frequency Roll Off Via Headphone Outputs (and line output for the D5)
To be honest, I would not choose any of these DACs for myself except for voice chat or a similar non-critical application. And for that use, the FiiO D5 is probably the winner because of its extra controls and features. Otherwise all three C-Media based DACs offer relatively poor audio performance. It’s likely most computers have better sound hardware built in—especially if it’s by Realtek, Intel, or Creative. The relatively poor performance of these three C-Media DACs also makes me wonder about C-Media in general. Some high end DACs, like the Schiit Audio Bifrost, use C-Media chips and I have to wonder if they too have excessive jitter, etc? Check back soon for two more DAC reviews that offer better performance.