These are not the same size of amplifier: Onkyo Muse Y-50 has roughly 2.5x the power of Audiolab 6000A. That is about 4dB, 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 |
|---|
| Power | A | Onkyo Muse Y-50 has more power - 125W against 50W into 8 ohms. That is about 4dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| 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 | A | Onkyo Muse Y-50 is the quieter design on paper - 100dB against 76dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | evenly matched | Both have a DAC on board with much the same capability. |
| Streaming | A | Only Onkyo Muse Y-50 has AirPlay 2 and Chromecast. |
| Room to grow | B | Only Audiolab 6000A offers a pre-out/main-in loop - 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 Audiolab 6000A 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 24% less shelf area (1225cm² against 1605cm²). |
| Price | B | Audiolab 6000A costs less - $899 against $1,500 at list. |
| Watts per dollar | A | Onkyo Muse Y-50 is the cheaper watt - about $12 per watt against $18. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Onkyo Muse Y-50 B Audiolab 6000A
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 Muse Y-50 measures better, Audiolab 6000A costs about 40% 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-50 is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. 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 - Onkyo Muse Y-50 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 50 watts is already more than most people ever use, and the extra 75 watts would be headroom you pay for and never hear.
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.