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 | Mark Levinson No.5802 has more power - 125W against 100W into 8 ohms. That is about 1dB, which is a small step in loudness but real headroom on peaks. |
| Grip on hard loads | B | Mark Levinson No.5802 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 | McIntosh MSA5500 is the quieter design on paper - 110dB against 103dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | B | Both decode on board, but only Mark Levinson No.5802 handles DSD and MQA. |
| Streaming | A | Only McIntosh MSA5500 has AirPlay 2, Chromecast and Roon. |
| Phono stage | depends | McIntosh MSA5500 has a built-in phono stage and Mark Levinson No.5802 does not. Decisive if you own a turntable, completely irrelevant if you do not - and an outboard phono stage is easy to add later either way. |
| Room to grow | A | Only McIntosh MSA5500 offers a pre-out/main-in loop - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Price | A | McIntosh MSA5500 costs less - $8,000 against $8,500 at list. |
A McIntosh MSA5500 B Mark Levinson No.5802
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 - Mark Levinson No.5802 is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. If you play records, McIntosh MSA5500 saves you buying a phono stage; if you do not, ignore that row entirely.
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.