Bottlehead Crack (OTL kit) vs SMSL H300

Both are desktop amplifiers, $375 against $296. This page puts them side by side on the only three things a maker can be held to — power, output impedance and noise — and then asks the question that actually matters: which headphones do they treat differently?

The SMSL H300 reaches 100 dB on 567 of the 567 models here, the Bottlehead Crack (OTL kit) on 565.

A figure marked not published is missing from the maker’s own material, which is not the same as being good or bad. Where one of these two publishes a number and the other does not, the comparison on that axis cannot be made at all — and saying so is more useful than guessing.

Both makers publish a power rating, which is less common than the table above makes it look: of the 280 sources here, 209 publish a figure at at least one load and only 2 publish one at all four. Bottlehead Crack (OTL kit) publishes at 300 Ω; SMSL H300 at 32 Ω. Every other row is worked out from those — between two published loads, or beyond them holding voltage constant, which understates rather than flatters.

So the two columns are not equally firm row by row: at 300 Ω only the Bottlehead Crack (OTL kit) figure is the maker’s own and at 32 Ω only the SMSL H300 figure is the maker’s own. On those rows the derived number is the one to doubt first.

What each of these labels means, and why a derived figure is still worth printing, is set out in how this data was built.

2 headphones reach 100 dB on the SMSL H300 but not on the Bottlehead Crack (OTL kit) — Moondrop PARA, Symphonium Titan.

567 headphones are left alone by the SMSL H300 under the one-eighth rule but coloured by the Bottlehead Crack (OTL kit) (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 564 more).

565 of the 567 models here reach 100 dB on both. That is a power count and nothing more; whether either source suits a given headphone also depends on the two lines above.

The counts above say how many models the two treat differently. This says by how much. The same 8 headphones appear on every page of this kind, ordered from the easiest to drive to the hardest, so a row can be read across pages as well as across columns. Headroom is at a 100 dB SPL peak.

The widest gap on the list is the Campfire Audio Andromeda 2020: SMSL H300 has +32 dB of headroom there against +13 dB. 19 dB is about 74 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 SMSL H300 because neither maker publishes no output noise figure. That is a gap in the specification, not a quiet amplifier, and it is left blank here rather than filled with a plausible number.

The Bottlehead Crack (OTL kit) costs $79 more than the SMSL H300, and on these three axes the money buys nothing: among the 567 models here there is not one that the Bottlehead Crack (OTL kit) handles and the SMSL H300 does not — not on power, not on the one-eighth rule, not on hiss. The traffic runs the other way: the cheaper SMSL H300 drives 2 models to 100 dB and leaves 567 alone under the one-eighth rule that the Bottlehead Crack (OTL kit) does not.

Everything in this paragraph counts only figures the two makers published. An advantage on an axis one of them leaves blank cannot be counted, and is not counted — how often that happens is its own page.

Each has a page of its own with every power figure traced to what the maker published and a full headphone list: Bottlehead Crack (OTL kit) and SMSL H300. Or put either against your own headphones in the source comparison tool.