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 | evenly matched | Effectively the same output - 125W against 110W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Grip on hard loads | A | Onkyo Muse Y-50 holds up better into a 4-ohm load: its output nearly doubles to 250W, where the other increases strongly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Noise floor | B | 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 | B | 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 | A | Only Onkyo Muse Y-50 offers a subwoofer output - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Amplifier class | depends | Onkyo Muse Y-50 is Class D and Onkyo Icon A-50 is Class A/B. Class D runs cool and draws almost nothing at idle; Class A/B runs warm and is the long-established mainstream choice. Modern examples of both measure well - judge by the rest of the page. |
| Shelf space | depends | Onkyo Muse Y-50 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 | A | Onkyo Muse Y-50 costs less - $1,500 against $1,600 at list. |
A Onkyo Muse Y-50 B Onkyo Icon A-50
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?
Neither runs away with it - they trade advantages. Let the "depends" rows and the speakers you already own settle it. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Onkyo Muse Y-50 is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating.
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.