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 | Rotel A14 MKII has more power - 80W against 60W into 8 ohms. That is about 1.2dB, which is a small step in loudness but real headroom on peaks. |
| Room size | depends | We rate Rotel A12 MKII the better fit for desk or near-field listening and a small room, and Rotel A14 MKII for a mid-size room, a large room and a very large room. Match the amplifier to the room you actually have, not the one you want. |
| Noise floor | evenly matched | Much the same signal-to-noise ratio (100dB vs 100dB). |
| Built-in DAC | B | Both decode on board, but only Rotel A14 MKII handles MQA. |
| Streaming | evenly matched | Only Rotel A14 MKII has Roon. Neither list is longer in a way that matters - check the one service you actually pay for. |
| Analogue inputs | evenly matched | The same number of line-level inputs (4). |
| Room to grow | evenly matched | The same expansion options on both. |
| Price | A | Rotel A12 MKII costs less - $1,100 against $1,600 at list. |
A Rotel A12 MKII B Rotel A14 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?
The usual trade-off: Rotel A14 MKII measures better, Rotel A12 MKII costs about 31% less. With most speakers in most rooms that gap is smaller in practice than it looks here. Think about the whole system: the roughly $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.