These are not the same size of amplifier: Musical Fidelity M6si500 has roughly 5x the power of Cambridge Audio Edge A. That is about 7dB, 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 | A | Musical Fidelity M6si500 has more power - 500W against 100W into 8 ohms. That is about 7dB - a different class of amplifier rather than a bigger version of the same one, and far more than most rooms will ever ask for. |
| Room size | depends | We rate Musical Fidelity M6si500 the better fit for a very large room, and Cambridge Audio Edge A for desk or near-field listening, a small room and a mid-size room. Match the amplifier to the room you actually have, not the one you want. |
| Built-in DAC | B | Cambridge Audio Edge A has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Analogue inputs | A | Musical Fidelity M6si500 takes more analogue sources - 4 against 3. |
| Use with a TV | depends | Only Cambridge Audio Edge A has HDMI ARC, so the television can drive it directly and one remote controls the volume. If the system is for music only, this changes nothing. |
| Headphones | depends | Only Cambridge Audio Edge A has a headphone output. Worth something if you listen late, nothing if you never do. |
| Amplifier class | depends | Musical Fidelity M6si500 is Class A/B and Cambridge Audio Edge A is Class XA. Class A/B runs warm and is the long-established mainstream choice. Modern examples of both measure well - judge by the rest of the page. |
| Price | A | Musical Fidelity M6si500 costs less - $5,499 against $6,499 at list. |
| Watts per dollar | A | Musical Fidelity M6si500 is the cheaper watt - about $11 per watt against $65. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Musical Fidelity M6si500 B Cambridge Audio Edge A
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?
Musical Fidelity M6si500 is the easier recommendation: it leads on most of the measured areas and costs less. Take Cambridge Audio Edge A if one of the "depends" rows above describes your system. 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 - Musical Fidelity M6si500 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 400 watts would be headroom you pay for and never hear - we rate Musical Fidelity M6si500 poorly for near-field use for exactly that reason. If this sits under a television, Cambridge Audio Edge A is the one to buy - HDMI ARC means the TV remote controls the volume and there is no second box in the way.
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.