Short answer
Both are desktop amplifiers, $375 against $600.
The iFi iCAN Pro reaches 100 dB on 567 of the 567 models here, the Bottlehead Crack (OTL kit) on 565.
| Specification | Bottlehead Crack (OTL kit) | iFi iCAN Pro |
|---|---|---|
| Power into 32Ω | 271 mW | 4.0 W |
| Power into 150Ω | 403 mW | 1.2 W |
| Power into 300Ω | 333 mW | 600 mW |
| Power into 600Ω | 227 mW | 300 mW |
| Output impedance | 120.0 Ω | 0.5 Ω unverified |
| Output noise | not published | 25 µV unverified |
| Price | $375 | $600 |
| Headphones it reaches 100 dB on out of 567 | 565 | 567 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Load | Bottlehead Crack (OTL kit) | iFi iCAN Pro |
|---|---|---|
| 32 Ω | Derived | Unverified |
| 150 Ω | Derived | Unverified |
| 300 Ω | Published | Unverified |
| 600 Ω | Derived | Unverified |
iFi iCAN Pro publishes no electrical specification at all. That is true of 10 of the 280 sources here, and the figures in that column come from independent measurement rather than from a maker document — which is not worse, but it is not the same thing, and it cannot be checked against anything the maker will stand behind.
The Bottlehead Crack (OTL kit) column does stand on a power rating its maker printed, at one of these four loads at least. Reading the two straight across sets one kind of claim against another, and nobody has written down the conditions of both side by side.
2 headphones reach 100 dB on the iFi iCAN Pro but not on the Bottlehead Crack (OTL kit) — Moondrop PARA, Symphonium Titan.
565 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 Campfire Audio Andromeda 2020: iFi iCAN Pro has +25 dB of headroom there against +13 dB. 12 dB is about 15 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Bottlehead Crack (OTL kit) and iFi iCAN Pro because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | Bottlehead Crack (OTL kit) headroom | iFi iCAN Pro headroom | Bottlehead Crack (OTL kit) hiss | iFi iCAN Pro hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +33 dB damping | +45 dB | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +13 dB damping | +25 dB | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +26 dB damping | +34 dB | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +27 dB damping | +31 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +14 dB damping | +26 dB | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +22 dB damping | +24 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +17 dB damping | +20 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | +7 dB damping | +17 dB | not published | not published |
The iFi iCAN Pro costs $225 more than the Bottlehead Crack (OTL kit). Out of the 567 models here, that difference buys 2 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 has a page of its own with a full headphone list and the provenance of every figure — worth opening here, because iFi iCAN Pro has published no electrical specification at all and everything above comes from independent measurement: Bottlehead Crack (OTL kit) and iFi iCAN Pro.