These are not the same size of amplifier: Rotel Diamond RA-6000 has roughly 2x the power of McIntosh MA5300. That is about 3dB, 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 | B | Rotel Diamond RA-6000 has more power - 200W against 100W into 8 ohms. That is about 3dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate McIntosh MA5300 the better fit for desk or near-field listening, a small room and a mid-size room, and Rotel Diamond RA-6000 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 increases strongly (160W and 350W). |
| Noise floor | A | McIntosh MA5300 is the quieter design on paper - 110dB against 103dB. 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 | evenly matched | Only Rotel Diamond RA-6000 has Roon. Neither list is longer in a way that matters - check the one service you actually pay for. |
| Analogue inputs | A | McIntosh MA5300 takes more analogue sources - 5 against 4. |
| Room to grow | A | Only McIntosh MA5300 offers a pre-out/main-in loop - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Shelf space | depends | Rotel Diamond RA-6000 takes up about 20% less shelf area (1979cm² against 2488cm²), and it is 103mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Rotel Diamond RA-6000 costs less - $4,500 against $6,000 at list. |
| Watts per dollar | B | Rotel Diamond RA-6000 is the cheaper watt - about $23 per watt against $60. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A McIntosh MA5300 B Rotel Diamond RA-6000
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?
McIntosh MA5300 is ahead, but on only 1 of the measured areas, and it costs about 33% more. That is a lot of money for a narrow margin - Rotel Diamond RA-6000 is the sensible buy unless a specific feature above decides it for you. 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 - Rotel Diamond RA-6000 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 100 watts is already more than most people ever use, and the extra 100 watts would be headroom you pay for and never hear - we rate Rotel Diamond RA-6000 poorly for near-field use for exactly that reason. Think about the whole system: the roughly $1,500 saved by taking the cheaper one would buy better speakers or a subwoofer, which does more for the sound than the difference between two competent amplifiers.
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.