One is a streaming all-in-one and the other is an amplifier. Judge them on how many boxes you want and what you already own, not on the spec sheet alone.
| Area | Better | Why |
|---|
| Power | B | WiiM Amp Ultra has more power - 100W against 60W into 8 ohms. That is about 2.2dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output nearly doubles (120W and 200W). |
| Built-in DAC | evenly matched | Both have a DAC on board with much the same capability. |
| Streaming | evenly matched | Only WiiM Amp has AirPlay 2. Neither list is longer in a way that matters - check the one service you actually pay for. |
| Room to grow | evenly matched | The same expansion options on both. |
| Shelf space | depends | WiiM Amp takes up about 19% less shelf area (420cm² against 522cm²), and it is 39mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | WiiM Amp costs less - $299 against $549 at list. |
A WiiM Amp B WiiM Amp Ultra
depends neither is better in the abstract - it turns on your room, your system or how you will use them. Only specs published for both amplifiers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
WiiM Amp Ultra is ahead, but on only 1 of the measured areas, and it costs about 84% more. That is a lot of money for a narrow margin - WiiM Amp is the sensible buy unless a specific feature above decides it for you. Start with the room. In a large or open-plan room, or with speakers that are hard to drive - low sensitivity, or an impedance that dips - WiiM Amp Ultra has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 60 watts is already more than most people ever use, and the extra 40 watts would be headroom you pay for and never hear. Think about the whole system: the roughly $250 saved by taking the cheaper one would buy better speakers or a subwoofer, which does more for the sound than the difference between two competent amplifiers.
What a spec sheet cannot show: how either sounds with your speakers, how the controls feel day to day, and what the app is like to live with - which is where most all-in-one amplifiers are actually won or lost. Power figures are the manufacturers' own and are not measured to a common standard, so treat small differences as noise. If you can hear both, that will tell you more than any row above.