The Best DACs for High-Impedance Headphones

Almost every headphone-power specification published anywhere is quoted into 32 ohms, because 32 ohms is what most headphones sold are. If yours is a 250 or 300 or 600 ohm design, that number is close to useless to you, and the useful number is in a column most manufacturers leave blank. So this page throws away the 32 Ω column entirely. Four of the five products below publish a 300 Ω figure; one publishes a 600 Ω figure; and the ranking is what is left when you read only those.

Why the 32 Ω figure cannot be scaled

A headphone amplifier is a voltage source into a resistive-ish load, so power follows P = V² / R. Hold the voltage constant and multiply the impedance by about 9.4 (32 → 300), and the power divides by the same factor. That is the floor on how badly the number can fall. In practice it falls by slightly more than that, because every amplifier here hits a voltage ceiling before it hits a current ceiling into a high-impedance load. Here is what the makers themselves publish:

Every FiiO figure above carries the condition “THD+N < 1%”, which is FiiO’s wording and is a loose distortion limit for a power rating. The iFi and Cambridge figures carry no distortion condition at all. Those are not equivalent measurements, and we are not going to pretend they are.

The number to actually compare: volts, not milliwatts

A high-impedance headphone is a voltage problem. Its own specification sheet almost certainly quotes sensitivity in dB per volt rather than dB per milliwatt, because at 300 Ω that is the sane unit. So the useful conversion is from each published power figure back to the voltage it implies:

1. FiiO K9 Pro ESS — the only watt-level 300 Ω figure here

FiiO publishes ≥ 1.1 W into 300 Ω from the balanced outputs and ≥ 281 mW from the 6.35 mm jack. The second of those numbers alone beats every other balancedfigure on this page except the K11’s, which is the clearest statement of where this product sits. It also has a three-position gain switch published as −3 dB / 6 dB / 16 dB, and that matters more on high-impedance headphones than anywhere else, because you want the gain stage doing the work rather than the volume control sitting near its top. The cost is that it is by a wide margin the most expensive box here, and that its 300 Ω advantage over the K7 is 2× single-ended — real, but not transformative.

2. FiiO K7 — best single-ended 300 Ω figure for the money, with one blank

140 mW into 300 Ω from the 6.35 mm socket, which is 2.3× what the K11 publishes from the same socket, from a box using the same THX AAA 788+ amplifier modules as the K9 Pro ESS. If you are plugging a 250 or 300 Ω headphone into a single-ended jack, this is the value pick.

And here is the odd part: the K7 publishes no balanced figure at 300 Ω at all. It publishes ≥ 2,000 mW balanced into 32 Ω and then stops. Its cheaper sibling publishes both. We are not going to estimate the missing number from the 32 Ω one, because the whole argument of this page is that you cannot scale between those columns reliably. It costs the K7 a place.

3. FiiO K11 — the balanced-socket bargain

≥ 250 mW into 300 Ω balanced, 8.7 V RMS, from the cheapest box on this page. Use the 6.35 mm jack instead and you get 60 mW, the weakest single-ended 300 Ω figure here — so this is a product whose suitability depends entirely on which cable you own. It also publishes a line-out signal-to-noise of ≥ 126 dB against the K7’s ≥ 116 dB, which is a genuinely surprising direction for that comparison to run and the reason we gave those two their own page.

4. FiiO K11 R2R — close on power, expensive on distortion

≥ 220 mW at 300 Ω balanced in OS mode puts it within 12% of the standard K11 on the only axis this page cares about. The reason it ranks below it is the figure FiiO publishes for its line out: “About 0.025%” THD+N — including the word “About”, which is FiiO’s and not ours — against 0.0005% for the K7. That is roughly fifty times the distortion, and it is the honest price of a discrete resistor-ladder converter. Buy it because you want an R2R DAC, not because you want 300 Ω power.

5. iFi ZEN DAC 3 — the only 600 Ω number on this site

> 18 mW at 600 Ω, single-ended. It is the smallest power figure on this page and it is also the only one that exists, which is why the product is here at all. 18 mW into 600 Ω works out to about 3.3 V RMS, and whether that is enough depends entirely on your headphone’s sensitivity — for an efficient 600 Ω dynamic design it plausibly is; for an insensitive one it is not. iFi also publishes > 390 mW at 64 Ω balanced and nothing at 300 Ω, so the middle of the range is a blank.

The honest summary of this pick: it is first in its bracket by default, and the bracket has one entrant.

The product that recommends 600 Ω and publishes nothing at 600 Ω

The Cambridge DacMagic 200M is not in the picks above, and the reason is worth stating because it is the single most pointed gap we found. Cambridge publishes a recommended headphone impedance of 10 Ω – 600 Ω, which is an explicit invitation to plug in a 600 Ω headphone. The power figures it publishes are > 300 mW into 32 Ω and > 65 mW into 150 Ω. There is no 300 Ω figure and no 600 Ω figure. So the one maker here that tells you in writing that it supports the load this page is about is also the one that tells you nothing about how it performs into it. It is an excellent DAC for a hi-fi rack and we rank it as one on our under-$500 roundup; on this specific question its sheet is silent.

The Fosi SK02 has the same shape of problem from the other direction: it publishes a headphone impedance match of 16 – 300 Ω, so it claims the top of this page’s range, and then publishes power only at 32 Ω — and with no distortion condition attached to either figure.

Output impedance, and why we cannot rank on it

The received rule for headphone amplifiers is that the amplifier’s output impedance should be under about an eighth of the headphone’s, so that the headphone’s own impedance swings do not bend the frequency response. The good news for high-impedance owners is that this is the one group the rule barely troubles: at 300 Ω the budget is around 37 Ω, and at 600 Ω it is 75 Ω, which almost any competent solid-state output clears.

The bad news is that we cannot verify it, because not one of the seven products in the table above publishes a headphone output impedance. Cambridge publishes a line output impedance — < 50 Ω unbalanced, < 100 Ω balanced — and that is a different socket for a different job. So the damping rule is a reason to relax about high-impedance headphones rather than a criterion we can rank five products on, and the opposite case is where it bites: low-impedance multi-driver in-ears, where the budget is a couple of ohms and nobody publishes the number either.

How we would choose

Work out which socket you will actually use first, because it reorders everything above. Balanced cable: the K11 at 8.7 V is startling value and the K9 Pro ESS at 18.2 V is the answer if the K11 is not enough. Single-ended only: the K7 at 6.5 V, then the K9 Pro ESS at 9.2 V if you want more. A 600 Ω headphone: the ZEN DAC 3, because it is the only product here whose maker has said anything at all about that load, and if 3.3 V is not enough for your headphone then nothing on this site has been documented to do better.

If you are still deciding whether you need a separate box at all, our guide to headphone power and impedance has the SPL arithmetic, and our general DAC/amp roundup ranks the same field on the 32 Ω column for everyone whose headphones are normal.