Both are desktop amplifiers, $660 against $699. This page puts them side by side on the only three things a maker can be held to — power, output impedance and noise — and then asks the question that actually matters: which headphones do they treat differently?
The Grace Design m900 reaches 100 dB on 567 of the 567 models here, the Rupert Neve RNHP on 566.
| Specification | Grace Design m900 | Rupert Neve RNHP |
|---|---|---|
| Power into 32Ω | 1.0 W | 262 mW |
| Power into 150Ω | 228 mW | 175 mW |
| Power into 300Ω | 115 mW | 88 mW |
| Power into 600Ω | 57 mW | 44 mW |
| Output impedance | 0.08 Ω | 0.08 Ω |
| Output noise | 5.01 µV | 8.03 µV |
| Price | $660 | $699 |
| Headphones it reaches 100 dB on out of 567 | 567 | 566 |
A figure marked not published is missing from the maker’s own material, which is not the same as being good or bad. Where one of these two publishes a number and the other does not, the comparison on that axis cannot be made at all — and saying so is more useful than guessing.
1 headphone reaches 100 dB on the Grace Design m900 but not on the Rupert Neve RNHP — Symphonium Titan.
88 headphones stay below the audible-hiss threshold on the Grace Design m900 but cross it on the Rupert Neve RNHP (64 Audio Aspire 1, 64 Audio Ocean, 64 Audio Volur, 85 more).
566 of the 567 models here reach 100 dB on both. That is a power count and nothing more; whether either source suits a given headphone also depends on the two lines above.
Each has a page of its own with every power figure traced to what the maker published and a full headphone list: Grace Design m900 and Rupert Neve RNHP. Or put either against your own headphones in the source comparison tool.