These are not the same size of amplifier: McIntosh MI254 has roughly 2x the power of Sonos Amp Multi. That is about 3dB, so it is a question of room size and how hard your speakers are to drive, not of one being the better amplifier.
| Area | Better | Why |
|---|
| Zones | B | Sonos Amp Multi feeds more rooms - 4 stereo zones against 2. This is usually the deciding row: a zone you do not have cannot be made up for with watts, and adding one later means a second chassis. |
| How the power is measured | evenly matched | Both publish an all-channels-driven rating, so the watts row above is a fair comparison rather than two different tests side by side. |
| Power | A | McIntosh MI254 has more power - 250W against 125W into 8 ohms. That is about 3dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Bass control | B | Sonos Amp Multi has the higher damping factor (400 vs 85), which usually means a tighter grip on a woofer. Above about 100 the returns flatten out, so read this as a tendency rather than a ranking. |
| Noise floor | B | Sonos Amp Multi is the quieter design on paper - 114dB against 100dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | B | Sonos Amp Multi has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Analogue inputs | A | McIntosh MI254 takes more analogue sources - 4 against 2. |
| Shelf space | depends | Sonos Amp Multi takes up about 51% less shelf area (1158cm² against 2369cm²), and it is 268mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Sonos Amp Multi costs less - $3,500 against $6,000 at list. |
A McIntosh MI254 B Sonos Amp Multi
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?
Sonos Amp Multi is the easier recommendation: it leads on most of the measured areas and costs less. Take McIntosh MI254 if one of the "depends" rows above describes your system. 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 - McIntosh MI254 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 125 watts is already more than most people ever use, and the extra 125 watts would be headroom you pay for and never hear. If you already own a DAC or a streamer, the built-in one is money you are paying twice for, and McIntosh MI254 becomes the more rational buy.
What a spec sheet cannot show: how either sounds with your speakers, how the controls feel day to day, and how the zone control and setup behave once it is in a rack - which is where a distribution amplifier is actually lived with. 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.