Overview of Schiit Fulla 2 based AKM AK4490 – compact USB DAC and headphone amplifier

External USB DAC Schiit Fulla 2 is absolutely different from its predecessor, Schiit Fulla. Much has changed. Remained compact and easy to use. This is the only manufacturer model, operating in UAC1 mode (does not require drivers). That is, Schiit Fulla 2 can be connected to anything, including a mobile phone, tablet, Mac, PC, and immediately listen to music.

It is interesting that if Fulla did not have a smartphone during the test (there was not enough current for the card), then Fulla 2 immediately found and earned! To prevent the battery from melting, especially when connecting low-sensitivity headphones, any additional 5-volt charging for mobile phones, a stand-alone battery (powerbank) or a 220 V adapter can be connected to the additional input of the Full-2 Micro-USB card, from which only power is taken. When you connect to a laptop or computer, all this becomes unnecessary, and there is enough USB port.


Overview of Schiit Fulla 2 based on AKM AK4490

Should I regret withdrawing the first card? Absolutely not worth it. Schiit Fulla 2 is much more interesting in all respects! There’s a full-sized headphone output, and a clean line-out, and an adjustable linear, and extra power, and a comfortable volume control. The filling is at least as good: instead of the old AK4396, now the new AK4490 converter. Instead of a signal-to-noise ratio of 103 dB, 105 dB are declared at 1 VRMS. According to our measurements – 112-114 dB with 2 VRMS.

Technical specifications of Schiit Fulla 2

Operating frequency range 20 Hz – 20 kHz (0.1 dB, 2 Hz – 200 kHz, -3 dB)
Maximum power with load impedance
  • 16 Ω: 550 mW RMS/ channel
  • 32 ohm: 360mW RMS/ channel
  • 50 Ω: 230 mW RMS/ channel
  • 300 ohms: 40mW RMS/ channel
Harmonic coefficient is less than 0.003% (20 Hz – 20 kHz, 1 V RMS)
Intermodulation Distortion less than 0.002% (CCIF)
Signal to noise ratio more than 105 dBA (1 V RMS)
Interaction is less than -75 dB (20 Hz – 20 kHz)
Amp impedance less than 0.5 Ohm
Formats from 16 bits / 44.1 kHz to 24 bit / 96 kHz
USB Receiver C-Media CM6631A, in UAC1 mode, without drivers
Output stage TI LMH6643x2 (one per channel)
DAC AKM AK4490; Filter on TI OPA1662
Power Source USB or external 5 V adapter
Power consumption ≈0.8 W
Dimensions 89 × 63.5 × 35 mm
Mass 0.26 kg
Cost ≈ $ 120

Made in the USA.

Schiit Fulla 2 – price. Where is the best place to buy?

The recommended retail price for the Schiit Fulla 2 in the US is about $ 100. At this cost, you can order it on Amazon. Plus Shipping, so the total cost of Schiit Fulla 2 when ordering on Amazon will be about $ 110. I would not recommend ordering anywhere else except on Amazon. Since you are less likely to find cheaper, and if you do not take into account the fact that Amazon is probably the most reliable online store, it still very often provides free shipping.

Appearance

Overview of Schiit Fulla 2 based on AKM AK4490

The case is completelymetallic! Slots on the top panel perform a decorative role: the meter does not have a picometer, there is no LED indication.

Overview of Schiit Fulla 2 based on AKM AK4490

There are two mini-jacks on the rear panel: an unregulated line output and an adjustable line output. One Micro-USB connector is for connecting the device, another one is for power only, and the power is not necessary to connect. We tried to connect a powerful battery, and this did not affect either sound or measurement. Extra power is needed only in the case of mobile devices – so as not to plant their internal battery. We checked that everything works correctly: power is only transferred to an external source.

Some users have had complaints about having only three legs on the bottom panel. Although this provides maximum stability, but when connecting headphones you want to press the case to the table, and then it can lose stability. For us, the claim is rather ridiculous: after all, you can either remove all the regular rubber bands, or take a wide piece of rubber (or cut four identical small pieces) and strengthen with a few drops of glue.

Schiit Fulla 2 based on AKM AK4490

The volume control here is analog. Of course, any such controller, even the most expensive, will have at the beginning of its course a spread of loudness between the channels. This was also one of the claims to the card from Western users. The inconvenience usually arises if the user has very sensitive headphones, to which he for some reason takes an amplifier of enormous power. Then you have to listen to everything at 1% -2% loudness, it’s hard to catch the desired volume in the most vulnerable area of ​​the regulator’s operation.

Here to Audioquest Dragonflythere are no complaints: because there is no regulator at all! Use the volume slider in the media player and enjoy the sound. Yes, there will be interference with digital data, but there will always be an ideal balance of channels. If you like this idea, just set the Fulla 2 volume to maximum and adjust it from the player. Thus, you generally turn off the variable resistor from the signal circuit.

On the PCB Fulla 2 there is a funny inscription: not just a dongle anymore.

Schiit Fulla 2 based on AKM AK4490

AKM AK4490 today is everywhere, from cheap devices to Hi-End with a lot of zeros in the price tag. Therefore, everything depends on how it is “cooked” by the manufacturer. Here on the board are visible 3 quartz oscillators. The scheme is nonstandard, not from datasheet. Actually, Americans always have their own ideology on circuitry, and it’s very well audible.

Schiit Fulla 2 based on AKM AK4490

The only complaint to the device that can be is the lack of support for Hi-Res formats: there is nothing higher than 96 kHz and there is no DSD, although the DAC and CM6631 all support it. What’s the matter? It’s about positioning. Fulla 2 is a cheap mass product. If you make it too tasty morsel, it will compete with older models of the line. In addition, for full-fledged drivers, most likely, you need to pay license fees C-Media, which will increase the cost of the device and break its elegance and simplicity.

Schiit Fulla 2 based on AKM AK4490

The OPA1662 dual-channel operational amplifier can be called the most popular in high-quality devices. Almost half the time in expensive solutions we see this amplifier. He has very low distortions: 0.00006% of the passport. Everything else looks just as good.

Schiit Fulla 2 based on AKM AK4490

But what is the “chip” of the developers, so this is a strange current buffer at the output, TI LMH6643 (2 pcs.). Perhaps he is responsible for the corporate character of the sound. In addition, the 550 mWRMS power per channel at 16 Ohms is very impressive!

We evaluated the sound of the device on the headphones Oppo PM-3, Sennheiser HD650, Beyerdynamic DT 990 Pro, Fostex TH-900, Grado 325is. This time we did not have competitors for comparison from the same price category, however we always compare the sound with the reference discrete amplifier, with parameters of 0.0002% distortion, signal / noise ratio 115 dB.

So, what about the sound of Schiit Fulla 2? It definitely has nothing to do with the sound of Schiit Fulla. There, the sound was very sharp, underlined, and in the pauses one could hear noise on sensitive headphones. The new Fulla 2 card has a detailed, but not rude sound, no noise at all. The sound is quite dynamic, not viscous. Closer to expensive devices. Any headphones that we had, perfectly combined with the amplifier. No problems with bass or with dynamics. Maybe the sound is not sufficiently specified, but for a budget device everything is just fine! Also, the sound has its own character, its own noble handwriting. Most likely, sound like the owners. In any case, the first responses from real owners in our conference were quite positive. More expensive devices than Schiit Fulla 2, still make sense, as the quality there continues to grow with the price tag, although not as fast, alas, as we would like.

What I want to say about standard drivers. We did not like how the foobar2000 card plays through the standard DirectSound: the sound is too soft. The best results are achieved through the WASAPI Event, the softness goes away. According to measurements, the numbers and spectra differ, but insignificantly. WASAPI coincides in spectrum with the original signal, DirectSound slightly diverges. Perhaps the static sine effect is weak, and you need to test the dynamic and transient characteristics.

We will make a reservation that this is true not for all sound cards, but only for those running a specific standard driver for the universal audio device (UAC1) inside Windows. What is inside there is with the data, why they are not bitwise, only the Microsoft team of programmers knows. Apparently, this driver was not written with increased care for sound. To minimize the impact of the driver on the sound, use the WASAPI output on the player. There is also ASIO4All, which internally uses WASAPI in the same way, converts ASIO calls into this format of working with the device. But with the mobile device, in special players in USB Audio mode, when the sound is output only by the player, not Android, the sound was absolutely normal. Live, detailed, in quality the same as WASAPI on PC. We draw conclusions.

Testing the Schiit Fulla 2 line output in RightMark Audio Analyzer

Test device Schiit Fulla 2
Operating mode 24-bit, 44 kHz
RMAA version 6.4.1 Pro
Filter 20 Hz – 20 kHz yes
Signal Conditioning yes
Level change -1.0 dB / -1.0 dB
Mono Mode none
Calibration frequency, Hz 1000
Polarity correct / correct

General results:

Uneven frequency response (in the range 40 Hz – 15 kHz), dB
+ 0,01, -0,12
Great
Noise level, dB (A)
– 114.3
Great
Dynamic range, dB (A)
114.1
Great
Harmonic distortion,%
0.0097
Very good
Harmonic distortion + noise, dB (A)
– 75.0
Medium
Intermodulation distortions + noise,%
0.012
Very good
Interconnection of channels, dB
– 108.4
Great
Intermodulation at 10 kHz,%
0.0095
Very good
Overall rating
Great

Testing the Schiit Fulla 2 headphone output in RightMark Audio Analyzer

Test device Schiit Fulla 2
Operating mode 24-bit, 44 kHz
RMAA version 6.4.1 Pro
Filter 20 Hz – 20 kHz YES
Signal Conditioning YES
Level change -1.0 dB / -1.0 dB
Mono Mode NO
Calibration frequency, Hz 1000
Polarity correct / correct

General results:

Uneven frequency response (in the range 40 Hz – 15 kHz), dB
+ 0,02, -0,13
Great
Noise level, dB (A)
– 112.0
Great
Dynamic range, dB (A)
112.1
Great
Harmonic distortion,%
0.015
Good
Harmonic distortion + noise, dB (A)
– 72.7
Medium
Intermodulation distortions + noise,%
0.015
Very good
Interconnection of channels, dB
– 102.5
Great
Intermodulation at 10 kHz,%
0.0099
Very good
Overall rating
Very good

The linear output was rated “Excellent” by RMAA. The headphone output is “Very good”. The nature of broadband interference in the distortion test remains unclear to us. It does not exist in the noise and dynamic range test, which eliminates problems with pick-ups in the measuring path. The passport should have less than 0.003% distortion at 1 VRMS. By the way, the manufacturer writes that it measures at Stanford Research SR1 (worth $ 10,000). Probably, in ideal conditions with laboratory nutrition, such figures will be obtained. In any case, the main value of the device is in its ability to reproduce music, rather than test sinuses of maximum scope.

Opinion of Schiit Fulla 2

During our detailed testing, we found out that the Schiit Fulla 2 USB DAC based on the AKM AK4490 DAC is a good device. The main advantage is its versatility and ease of use at an affordable price. It can be connected to anything from a mobile phone to a computer, and enjoy the sound right away, without any drivers. The downside of this simplicity is the lack of Hi-Res, a maximum of 24 bits of 96 kHz, although the DAC refers to the last generation and such support is possible to implement.

Schiit Fulla 2 based on AKM AK4490

The obvious plus of Schiit Fulla 2 is a powerful high-quality American sound, Made in USA. However, the DAC Schiit Fulla 2 succeeded also in functions. Here there is an interesting electronic stuffing, and on the possibilities of connection the manufacturer did not limit itself to the output to the headphones and the linear output: there is also an amplifier input, and 2 linear outputs, with or without adjustment. Also, there is an additional input for power, which allows you not to spend on all sorts of risky USB-splitters for connecting additional power.

If you generally like the approach of Americans Schiit, but stops the lack of Hi-Res and ASIO – look at the older models of this manufacturer, there it all is.



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