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 | NAD Masters Series M33 V2 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. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output nearly doubles (380W and 250W). |
| Noise floor | A | NAD Masters Series M33 V2 is the quieter design on paper - 120dB 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 NAD Masters Series M33 V2 has AirPlay 2, Roon and BluOS. |
| Phono stage | depends | NAD Masters Series M33 V2 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 | evenly matched | The same expansion options on both. |
| Amplifier class | depends | NAD Masters Series M33 V2 is Class D and Mark Levinson No.5802 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 | NAD Masters Series M33 V2 takes up about 21% less shelf area (1947cm² against 2454cm²), and it is 111mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | NAD Masters Series M33 V2 costs less - $7,399 against $8,500 at list. |
| Watts per dollar | A | NAD Masters Series M33 V2 is the cheaper watt - about $37 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 NAD Masters Series M33 V2 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?
NAD Masters Series M33 V2 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 V2 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. If you play records, NAD Masters Series M33 V2 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.