Originally published 3/29/22.
- 4/24/22. Article cleanup.
Shoutout to Sunny and the folks over at FiiO for sending over the K3! Full disclosure: I do not have to return this unit and will likely be including it in a giveaway of some sort.
Greetings mate and Welcome aboard! Stuart Charles here, HomeStudioBasics.com helping YOU make sound decisions leading to a beautiful audio experience that will make you fall in love with music (NOT gear) all over again, so…
I didn’t have a FiiO K3 Review on this site (go figure) but found myself using it quite a bit lately.
Because of that, I thought I’d do an official write-up of what has proven to be somewhat of a strange animal – something that’s gotten a lot of use in recent months here in my home, but perhaps not for the reasons you may be expecting.
So strap on (I mean in), and let’s see what all the fuss is about.
At A Glance
In The Box
FiiO K3 Compact Headphone Amplifier and USB Type-C DAC (Black)
USB Type-C Cable
4 x Spare Foot Pads (Note: The 2 pads you don’t see are on the bottom of the unit)
Quick Start Guide
Limited 1-Year Warranty
- Price: Check on Amazon! | Check B&H!
- Capability: Up to 32-bit/384kHz.
- Stereo Crosstalk: ≥70 dB (1 kHz).
- Outputs: 1x Coaxial, Line, 1x 3.5mm headphone jack, 1x 2.5mm balanced
- DSD Support: Yes, 64/128/256.
- Output Impedance: 1.04. What is Output Impedance?
- Output Power (Single Ended): 220 mW @ 16 Ohms, 120 mW @ 32 Ohms.
- Output Power (Balanced): 320 mW @ 16 Ohms, 200 mW @ 32 Ohms.
- Output Voltage: 7.39 Vp-p.
- Digital Outputs: Coaxial: RCA for 192 kHz, Support DSD64 DOP
Optical Out: Up to 96 kHz.
- Inputs: 1x Type-C USB.
- Signal-to-Noise Ratio: ≥113 dB.
- THD: ≤0.004%.
- Frequency Response: 20Hz to 80kHz.
- Op amp: 2 x OPA926.
- Low-pass filter: TI OPA1612.
- USB chip: XMOS XUF208.
- Dimensions: 2.8 x 2.3 x 0.9″ / 70.0 x 58.0 x 22.0 mm.
- Weight: 83 grams.
- Warranty: 1 year.
- Power: Bus powered, 5 VDC 500 mA.
- Features: Bass boost, Gain switch.
Back in 2019 when I first received the K3, I thought it was a nice upgrade from the E10K save for essentially one caveat: It didn’t provide as much power out of the unbalanced jack and isn’t the ideal choice for harder to drive headphones.
The sound differences between them are subtle but still noticeable. The K3 sounds a bit more refined and ever so slightly less grainy, but those differences aren’t ones you’ll likely care all that much about.
The reason is that I’m afforded the luxury of being able to discern them (the small differences) given how many DACS I have here in the studio.
Most people don’t and will never because they still have their sanity. I pretty much do not.
In addition to that, sound differences mostly stem from the source material and your headphones, not the DAC.
Even knowing about those subtle discrepancies, ultimately I still don’t care that much and mostly recommend DACS based on features and versatility.
Fortunately for us, the K3 is very versatile, especially at its current price point.
Let’s take a look.
On the front there’s the volume potentiometer, bass boost, gain switch, 3.5mm single-ended jack, and a 2.5mm balanced jack.
On the back panel, we’ve got a 3.5mm line out, a USB Type-C jack for use with your PC/Laptop, a Coaxial out, a USB 1.0/2.0 switch, and an optical out.
Then simply turn the unit off and disconnect everything (basically a reboot).
Now you can use USB 2.0, which supports DSD256 and up to 32-bit/384kHz. The USB 1.0 section only supports up to 24-bit/96kHz files. Related: What Is DSD In Audio?
The power-on indicator on the K3 also doubles as a sample rate indicator.
- Blue = 44.1kHz or 48kHz.
- Yellow = Anything above 48kHz.
- Green = DSD.
As mentioned in the open, the K3 is quite versatile and gets a lot of use in my studio right now. Let’s see what it’s capable of.
As a Converter
Some DACs only have coax and Toslink capabilities. If your computer doesn’t have those, you can use the K3 to convert the signal from USB to coax and then connect the other DAC to the K3.
So it would look like: PC/Laptop via USB > K3 via coax > other amp that has coax > headphones.
Another option you have is to run a Toslink cable from a receiver/TV into a converter. Then run a cable from the other end of the converter into the E10K or K3. Now you can use it with your TV!
Optical & Gaming?
FiiO also added an Optical/Toslink port! Use this to connect to a DAC using S/PDIF as mentioned above.
The only problem? It’s optical OUT only and not IN. This essentially means you can’t use it for Console Gaming which was a disappointment for me.
It would have made the K3 the most valuable entry-level DAC on the market in my opinion, but it still comes close!
With optical or coax out, you can hook it up to something like a receiver or speakers that have optical in or coax in.
A good example would be something like the Edifier R1280DB Powered Bluetooth Speakers which have both an optical input and a coaxial input.
Right now, the line-out function is getting quite a bit of use for me.
Though I don’t really use the K3 with headphones anymore (unless someone requests a demo), I have been using it full-time with my Presonus Eris e3.5s which are really versatile and incredibly affordable.
Just snag an RCA to mini cable and you’re set!
With this setup, I’ve got plenty of headroom and haven’t even turned the volume up to 11 yet. xD
In any event, the K3 is really versatile. You could also use the line out to a separate, more powerful amplifier later down the road as it can be just a DAC if you so choose.
With your phone
The K3 can technically be used with a smartphone, but depending on the make and model, you may get an error like “this device needs too much power.”
The good news is that if you have a phone with a Type-C port, this USB Type-C to USB 3.1 Gen1 Female Adapter Cable should work.
The K3 is bus-powered, so using it with your phone is technically possible, but you’ll be draining your phone’s battery since neither have batteries of their own to draw power from.
- K3/K9 Pro + Eris e3.5 Playlist: Here!
I’ve utilized both headphone jacks, mainly pairing the Sennheiser HD58X with a balanced 2.5mm cable which sounded great, but I mostly use the K3 single-ended.
Do note that most companies nowadays are gravitating towards 4.4mm as it seems 2.5 is slowly being phased out, much like the transition from micro USB to Type-C (as in the case of the original E10K to K3).
Even companies like FiiO themselves (who’ve relied heavily on 2.5mm in the past) are coming around to 4.4mm.
For instance, their K9 Pro has a 4.4mm jack on the front and I was pleasantly surprised to see them make the switch.
As mentioned previously, the sound of the K3 is similar to the E10K; i.e. crisp and detailed, but it’s less grainy and smoother overall.
The bass boost on the K3 can also be hit and miss; on some tracks it sounds great, but not so good on others.
You may be shocked to hear this, but I did an exhaustive A/B comparison between the K3 and K9 pro with the e3.5s and didn’t find much in the way of sound differences between them unbalanced.
Was there a difference balanced?
I’d venture to say yes, but it was such a minuscule one that it may have just been in my head. In other words, because I knew I was using balanced, my brain compensated by saying “This should sound better, so it is better.”
I will say the K9 Pro balanced into the 3.5s sounded ever so slightly cleaner and more lively, but this simply could have been a minor volume discrepancy error though I did my best to calibrate the levels appropriately.
This also could just be a case of, yes, a balanced connection is going to sound a bit better than an unbalanced one due to factors like reverse polarity and noise eradication.
If you’d like to hear some more in-depth sound impressions of the K3, the K3 vs. E10K article I did is rather enlightening and should solidify the main differences between them.
The ultimate question here is of value; is the K3 worth the asking price of just a shade over $100?
This is rather difficult because there are a few things the K3 does that the E10K does not:
The K3 supports DSD, balanced out for headphones, and can run files up to 32-bit/384kHz.
If you need those features, I still think it’s a good value given everything else it can do. If you don’t need DSD and don’t plan to use balanced headphones, the E10K has more power and can work with harder-to-drive headphones.
I don’t think the K3 is a good investment if you do have high impedance and/or lower sensitivity cans that need more juice.
Even with all that said, I may just end up bypassing both and investing in a K5 Pro since it’s even more versatile than these and has plenty of power for 99% of headphones.
This isn’t a petition for you to spend more money, it comes from a place of experience.
Before giving the E10K away to a Patron in 2021, I had owned the unit since 2018 and really enjoyed my time with it.
I still have the K3 here as it’s super convenient with my 3.5s, but I think the K5 Pro is overall a better investment for most people given that you’d likely just upgrade from the K3 anyway later on down the line.
The K5 Pro can do everything the K3 can do + more.
Well, that’s about it for today my friend! I hope you’ve enjoyed this FiiO K3 Review and came away with some valuable insight.
Questions? Comments? Requests? Did I miss the mark on something? Please let me know down below or Contact me!!
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Are you convinced the K3 is a true upgrade from the E10K? What are your thoughts/experience with the K5 Pro? I would love to hear from you. Until next time…
All the best and God bless,