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 | A | Onkyo Icon A-50 has more power - 110W against 75W into 8 ohms. That is about 1.7dB, which is a small step in loudness but real headroom on peaks. |
| Grip on hard loads | B | Onkyo Muse Y-40 holds up better into a 4-ohm load: its output nearly doubles to 150W, where the other increases strongly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Noise floor | A | Onkyo Icon A-50 is the quieter design on paper - 104dB against 100dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | A | Both decode on board. Onkyo Icon A-50 goes higher - 768kHz against 192kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Streaming | evenly matched | Only Onkyo Icon A-50 has Roon. 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. |
| Room correction | A | Onkyo Icon A-50 has room correction. In an awkward room that does more for the sound than any other difference on this page. |
| Amplifier class | depends | Onkyo Icon A-50 is Class A/B and Onkyo Muse Y-40 is Class D. Class A/B runs warm and is the long-established mainstream choice; Class D runs cool and draws almost nothing at idle. Modern examples of both measure well - judge by the rest of the page. |
| Shelf space | depends | Onkyo Muse Y-40 takes up about 25% less shelf area (1225cm² against 1636cm²), and it is 27mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Onkyo Muse Y-40 costs less - $1,000 against $1,600 at list. |
A Onkyo Icon A-50 B Onkyo Muse Y-40
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?
The usual trade-off: Onkyo Icon A-50 measures better, Onkyo Muse Y-40 costs about 38% less. With most speakers in most rooms that gap is smaller in practice than it looks here. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Onkyo Muse Y-40 is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. Think about the whole system: the roughly $600 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.