Different price classes - Denon AVR-X4800H costs roughly 1.7x what Yamaha AVENTAGE RX-A4A does. Expect it to lead on paper; the question is whether you will hear the difference through the speakers you own.
| Area | Better | Why |
|---|
| Power | evenly matched | Effectively the same output - 110W against 125W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Analogue inputs | B | Denon AVR-X4800H takes more analogue sources - 5 against 3. |
| Room to grow | evenly matched | The same expansion options on both. |
| Price | A | Yamaha AVENTAGE RX-A4A costs less - $1,600 against $2,799 at list. |
| Watts per dollar | A | Yamaha AVENTAGE RX-A4A is the cheaper watt - about $15 per watt against $22. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Yamaha AVENTAGE RX-A4A B Denon AVR-X4800H
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. Think about the whole system: the roughly $1,199 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.