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 | NAD Masters Series M33 has more power - 200W against 125W into 8 ohms. That is about 2dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate Mark Levinson No.5802 the better fit for desk or near-field listening, a small room and a mid-size room, and NAD Masters Series M33 for a very large room. Match the amplifier to the room you actually have, not the one you want. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output nearly doubles (250W and 380W). |
| Noise floor | B | NAD Masters Series M33 is the quieter design on paper - 120dB against 103dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | A | Both decode on board. Mark Levinson No.5802 goes higher - 384kHz against 192kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Streaming | B | Only NAD Masters Series M33 has AirPlay 2, Roon and BluOS. |
| Phono stage | depends | NAD Masters Series M33 has a built-in phono stage (MM,MC) 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 | evenly matched | The same expansion options on both. |
| Amplifier class | depends | Mark Levinson No.5802 is Class A/B and NAD Masters Series M33 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 | NAD Masters Series M33 takes up about 21% less shelf area (1949cm² against 2454cm²), and it is 111mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | NAD Masters Series M33 costs less - $6,499 against $8,500 at list. |
| Watts per dollar | B | NAD Masters Series M33 is the cheaper watt - about $32 per watt against $68. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Mark Levinson No.5802 B NAD Masters Series M33
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?
NAD Masters Series M33 is the easier recommendation: it leads on most of the measured areas and costs less. Take Mark Levinson No.5802 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 - NAD Masters Series M33 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 75 watts would be headroom you pay for and never hear - we rate NAD Masters Series M33 poorly for near-field use for exactly that reason. If you play records, NAD Masters Series M33 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.