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 | evenly matched | Effectively the same output - 200W against 200W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Grip on hard loads | A | Anthem STR holds up better into a 4-ohm load: its output nearly doubles to 400W, where the other increases strongly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Noise floor | A | Anthem STR 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. Rotel Diamond RA-6000 goes higher - 384kHz against 192kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| 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 | Anthem STR takes more analogue sources - 5 against 4. |
| Room to grow | evenly matched | The same expansion options on both. |
| Headphones | depends | Only Rotel Diamond RA-6000 has a headphone output. Worth something if you listen late, nothing if you never do. |
| Price | B | Rotel Diamond RA-6000 costs less - $4,500 against $5,000 at list. |
A Anthem STR 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?
The usual trade-off: Anthem STR measures better, Rotel Diamond RA-6000 costs about 10% 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 - Anthem STR is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating.
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.