No single best amplifier here. What decides it is what you have to drive, what you need to plug in, and how much of the system you want in one box.
| Area | Better | Why |
|---|
| Power | B | Rotel S14 has more power - 80W against 50W into 8 ohms. That is about 2dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate MOON 250i v2 the better fit for desk or near-field listening and a small room, and Rotel S14 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. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output nearly doubles (100W and 150W). |
| Noise floor | evenly matched | Much the same signal-to-noise ratio (101dB vs 100dB). |
| Built-in DAC | B | Rotel S14 has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Analogue inputs | A | MOON 250i v2 takes more analogue sources - 6 against 1. |
| Phono stage | depends | MOON 250i v2 has a built-in phono stage (MM) and Rotel S14 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. |
| Price | evenly matched | Priced within a few per cent of each other. |
| Watts per dollar | B | Rotel S14 is the cheaper watt - about $31 per watt against $48. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A MOON 250i v2 B Rotel S14
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?
Rotel S14 has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. 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 S14 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 50 watts is already more than most people ever use, and the extra 30 watts would be headroom you pay for and never hear - we rate Rotel S14 poorly for near-field use for exactly that reason. If you play records, MOON 250i 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.