These are not the same size of amplifier: Rotel A11 MKII has roughly 2x the power of Rotel DX-5. 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 A11 MKII has more power - 50W against 25W into 8 ohms. That is about 3dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Speaker load rating | A | Rotel DX-5 is rated down to 4 ohms against 8, so it is the safer partner for a low-impedance speaker. |
| Noise floor | A | Rotel DX-5 is the quieter design on paper - 100dB against 90dB. 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 DX-5 has Roon. Neither list is longer in a way that matters - check the one service you actually pay for. |
| Phono stage | depends | Rotel A11 MKII has a built-in phono stage (MM) and Rotel DX-5 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. |
| Use with a TV | depends | Only Rotel DX-5 has HDMI, so the television can drive it directly and one remote controls the volume. If the system is for music only, this changes nothing. |
| Shelf space | depends | Rotel DX-5 takes up about 63% less shelf area (610cm² against 1633cm²), and it is 95mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Rotel A11 MKII costs less - $799 against $1,699 at list. |
| Watts per dollar | B | Rotel A11 MKII is the cheaper watt - about $16 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 Rotel DX-5 B Rotel A11 MKII
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. 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 A11 MKII has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 25 watts is already more than most people ever use, and the extra 25 watts would be headroom you pay for and never hear. If you play records, Rotel A11 MKII 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.