Questyle M15i

Enough for IEMs and most full-size headphones, especially from the 4.4 mm output. Reviewers and owners drive an HD 650, HD 800 S, DT 1990 Pro, Focal Clear MG and efficient planars like the Ananda Nano to comfortable levels; a ZMF Caldera needed high gain and about 70% volume. Owners of power-hungry planars (a Dan Clark Noire X) found it short, and the only bench — of the near-identical M15 — measured modest output by dongle standards.

“Its ability to effortlessly power my Beyerdynamic DT1990 Pro MKII allows me to take those headphones out of the house and listen to them.”

derici2800, Head-Fi review

“Power is more then ample for my beloved HD650s”

Tiedren, r/headphones

“The Questyle is meant for IEMs. Not for power hungry full sized planars.”

kevintj604, r/headphones

Sources split along the line between review units and owners' units. Reviewers describe a black, hiss-free background even with sensitive IEMs. A group of owners report the dongle picking up interference — static, sizzling, random buzzing or ticking, often near a phone — and some returned or retired units over it.

Sources split three ways. One group hears it as neutral to slightly bright and unusually resolving for a dongle; a larger group hears a gentle warmth and smoothness; a third finds it bright-edged, thin and fatiguing — or no different from a cheap dongle in a level-matched comparison. One reviewer found the 3.5 mm output dull and the balanced output far better, which may explain part of the spread.

Sources split on whether 'simple' is a virtue. Supporters like the two outputs, the physical gain switch, Apple MFi support and DSD512, and several prefer leaving volume to the phone. Critics point out that a $250 dongle has no volume buttons, Bluetooth, EQ or app, and no Lightning cable in the box.

Sources split between day-to-day ease and connection fuss. It runs cool and pocketable for most, and its gain switch is liked. Against that: it powers on only once headphones are plugged in (swapping headphones can close the music app), it ignores some ordinary USB-C-to-C cables, owners report drop-outs when the phone or dongle moves, and a few find it large for phone use.

Reviewers praise the machined aluminium body and the glass window, including the Pentaconn 4.4 mm socket. Owners' reliability record is weaker: Amazon's owner reviews run negative on reliability, with units dying after weeks or months, and a few owners have seen the glass panel lift when a 4.4 mm plug is inserted.

Sources split, mostly along a familiar line. Reviewers and most owners call it worth its price for the power and sound it gets from a phone — more so at today's street price. Measurement-minded forum members see a basic dongle sold at a premium, and a few owners returned it for cheaper dongles they liked as much or more.