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 | evenly matched | Effectively the same output - 100W against 100W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Room size | depends | We rate Luxman L-505Z the better fit for a small room, and Cambridge Audio Edge A for 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 | B | Cambridge Audio Edge A holds up better into a 4-ohm load: its output nearly doubles to 200W, where the other increases strongly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Noise floor | evenly matched | Much the same signal-to-noise ratio (104dB vs 103dB). |
| 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 | Luxman L-505Z takes more analogue sources - 5 against 3. |
| Phono stage | depends | Luxman L-505Z has a built-in phono stage (MM and MC) and Cambridge Audio Edge A 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 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. |
| Room to grow | A | Only Luxman L-505Z offers a pre-out/main-in loop - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Amplifier class | depends | Luxman L-505Z 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 | B | Cambridge Audio Edge A costs less - $6,499 against $6,995 at list. |
A Luxman L-505Z 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?
Neither runs away with it - they trade advantages. Let the "depends" rows and the speakers you already own settle it. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Cambridge Audio Edge A is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. If you play records, Luxman L-505Z 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.