FiiO JM21 vs Shanling M1 Plus

Both are portable players, $199 against $209. 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 FiiO JM21 reaches 100 dB on 566 of the 567 models here, the Shanling M1 Plus on 564.

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. FiiO JM21 publishes at 32 Ω and at 300 Ω; Shanling M1 Plus 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 FiiO JM21 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 FiiO JM21 but not on the Shanling M1 Plus — Moondrop PARA, Symphonium Crimson.

14 headphones are left alone by the Shanling M1 Plus under the one-eighth rule but coloured by the FiiO JM21 (64 Audio Nio, 64 Audio Volur, Campfire Audio Andromeda 2023, 11 more).

564 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 Shure SE846: FiiO JM21 has +37 dB of headroom there against +31 dB. 6 dB is about 3.7 times the power, which matters for peaks rather than for how loud the music sits.

The hiss columns are empty for Shanling M1 Plus because that 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 Shanling M1 Plus costs $10 more than the FiiO JM21. Out of the 567 models here, that difference buys 14 more models left alone under the one-eighth rule.

It does not run one way only: the cheaper FiiO JM21 drives 2 models to 100 dB that the Shanling M1 Plus does not, which is the part worth checking against your own headphones before paying the difference.

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: FiiO JM21 and Shanling M1 Plus. Or put either against your own headphones in the source comparison tool.