Siblings in OSD's Nero range, so they share a design and a house sound. It comes down to power, features and price.
| Area | Better | Why |
|---|
| Power | evenly matched | Effectively the same output - 50W against 60W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output nearly doubles (100W and 120W). |
| Noise floor | evenly matched | Much the same signal-to-noise ratio (95dB vs 95dB). |
| Built-in DAC | evenly matched | Both have a DAC on board with much the same capability. |
| Room to grow | B | Only OSD Nero Stream XD2 offers preamp outputs - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Headphones | depends | Only OSD Nero Stream XD2 has a headphone output. Worth something if you listen late, nothing if you never do. |
| Shelf space | depends | OSD Nero Stream ARC takes up about 49% less shelf area (351cm² against 688cm²), and it is 97mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | OSD Nero Stream ARC costs less - $199 against $400 at list. |
| Watts per dollar | A | OSD Nero Stream ARC is the cheaper watt - about $4 per watt against $7. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A OSD Nero Stream ARC B OSD Nero Stream XD2
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 $201 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.