Short answer
Both are desktop DAC/amps, $100 against $143.
The FiiO K11 reaches 100 dB on 567 of the 567 models here, the Creative Sound Blaster X3 on 553.
| Specification | Creative Sound Blaster X3 | FiiO K11 |
|---|---|---|
| Power into 32Ω | 45 mW | 520 mW |
| Power into 150Ω | 35 mW | 115 mW |
| Power into 300Ω | 21 mW | 60 mW |
| Power into 600Ω | 14 mW | 30 mW |
| Output impedance | not published | 1.2 Ω |
| Output noise | not published | 2.8 µV |
| Price | $100 | $143 |
| Headphones it reaches 100 dB on out of 567 | 553 | 567 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Balanced | Creative Sound Blaster X3 | FiiO K11 |
|---|---|---|
| Socket | no separate rating | 4.4mm |
| Power into 32Ω | — | 1.4 W |
| Power into 300Ω | — | 250 mW |
| Output impedance | — | 2.4 Ω |
| Output noise | — | 4.9 µV |
| Headphones it reaches 100 dB on out of 567 | — | 567 |
Only the FiiO K11 has a separate balanced rating from its maker; through it, it reaches 100 dB on 567 of the 567 models here. The Creative Sound Blaster X3 may still have a balanced socket — its spec sheet simply gives no figure for one, so there is nothing to put beside it.
| Load | Creative Sound Blaster X3 | FiiO K11 |
|---|---|---|
| 32 Ω | Recomputed | Published |
| 150 Ω | Recomputed | Derived |
| 300 Ω | Derived | Published |
| 600 Ω | Recomputed | Derived |
Only one of these two columns starts from a power rating. FiiO K11 publishes one at 32 Ω and at 300 Ω; Creative Sound Blaster X3 publishes none at any of these four loads, so its column is worked out from power it published at other loads. Both are arithmetic on a maker’s own figures rather than guesses, and the method used for the Creative Sound Blaster X3 understates rather than flatters — but at 32 Ω and at 300 Ω are the only loads here at which its maker can be held to a figure.
14 headphones reach 100 dB on the FiiO K11 but not on the Creative Sound Blaster X3 — HiFiMAN HE-6se V2, HiFiMAN HE6 Remastered, HiFiMAN Susvara, 11 more.
553 of the 567 models here reach 100 dB on both.
Headroom is at a 100 dB SPL peak.
The widest gap on the list is the Shure SE846: FiiO K11 has +40 dB of headroom there against +25 dB. 15 dB is about 32 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Creative Sound Blaster X3 because that maker publishes no output noise figure.
| Headphone | Impedance | Needs | Creative Sound Blaster X3 headroom | FiiO K11 headroom | Creative Sound Blaster X3 hiss | FiiO K11 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +25 dB | +40 dB damping | not published | 23 dB |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +5 dB | +20 dB damping | not published | 3 dB |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +16 dB | +25 dB | not published | 1 dB |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +16 dB | +21 dB | not published | -3 dB |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +6 dB | +19 dB | not published | -4 dB |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +10 dB | +14 dB | not published | -10 dB |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +5 dB | +10 dB | not published | -14 dB |
| HiFiMAN Susvara | 60 Ω | 50 mW | -1 dB | +7 dB | not published | -16 dB |
The FiiO K11 costs $43 more than the Creative Sound Blaster X3. Out of the 567 models here, that difference buys 14 more models driven to 100 dB.
Nothing runs the other way: there is no axis here on which the cheaper of the two does better.
Only published figures count here; blank axes are counted separately.
Each in full: Creative Sound Blaster X3 and FiiO K11.