Short answer
Both are desktop amplifiers, $375 against $449.
The Schiit Lyr+ reaches 100 dB on 567 of the 567 models here, the Bottlehead Crack (OTL kit) on 565.
| Specification | Bottlehead Crack (OTL kit) | Schiit Lyr+ |
|---|---|---|
| Power into 32Ω | 271 mW | 6.0 W |
| Power into 150Ω | 403 mW | 1.5 W |
| Power into 300Ω | 333 mW | 900 mW |
| Power into 600Ω | 227 mW | 450 mW |
| Output impedance | 120.0 Ω | 0.4 Ω |
| Output noise | not published | not published |
| Price | $375 | $449 |
| 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) | Schiit Lyr+ |
|---|---|---|
| 32 Ω | Derived | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Published | Published |
| 600 Ω | Derived | Published |
Both makers publish a power rating. Bottlehead Crack (OTL kit) publishes at 300 Ω; Schiit Lyr+ at 32 Ω, at 300 Ω and at 600 Ω. The other rows are worked out from those.
So the two columns are not equally firm row by row: at 32 Ω and at 600 Ω only the Schiit Lyr+ figure is the maker’s own. On those rows the derived number is the one to doubt first.
2 headphones reach 100 dB on the Schiit Lyr+ but not on the Bottlehead Crack (OTL kit) — Moondrop PARA, Symphonium Titan.
566 headphones are left alone by the Schiit Lyr+ under the one-eighth rule but coloured by the Bottlehead Crack (OTL kit) (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 563 more).
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 Shure SE846: Schiit Lyr+ has +51 dB of headroom there against +33 dB. 18 dB is about 66 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 Schiit Lyr+ because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | Bottlehead Crack (OTL kit) headroom | Schiit Lyr+ headroom | Bottlehead Crack (OTL kit) hiss | Schiit Lyr+ hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +33 dB damping | +51 dB | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +13 dB damping | +31 dB | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +26 dB damping | +36 dB | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +27 dB damping | +32 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +14 dB damping | +29 dB | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +22 dB damping | +26 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +17 dB damping | +21 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | +7 dB damping | +18 dB | not published | not published |
The Schiit Lyr+ costs $74 more than the Bottlehead Crack (OTL kit). Out of the 567 models here, that difference buys 2 more models driven to 100 dB and 566 more models left alone under the one-eighth rule.
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: Bottlehead Crack (OTL kit) and Schiit Lyr+.