Both are dongles, $66 against $69. 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 iBasso DC03 Pro reaches 100 dB on 560 of the 567 models here, the ddHiFi TC35Pro (Mountain2) on 554.
| Specification | ddHiFi TC35Pro (Mountain2) | iBasso DC03 Pro |
|---|---|---|
| Power into 32Ω | 65 mW | 98 mW |
| Power into 150Ω | 14 mW | 21 mW |
| Power into 300Ω | 6.9 mW | 10 mW |
| Power into 600Ω | 3.5 mW | 5.2 mW |
| Output impedance | not published | 0.12 Ω |
| Output noise | not published | 0.9 µV |
| Price | $66 | $69 |
| Headphones it reaches 100 dB on out of 567 | 554 | 560 |
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.
6 headphones reach 100 dB on the iBasso DC03 Pro but not on the ddHiFi TC35Pro (Mountain2) — HiFiMAN HE-6se V2, HiFiMAN HE6 Remastered, HiFiMAN Susvara, 3 more.
554 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: ddHiFi TC35Pro (Mountain2) and iBasso DC03 Pro. Or put either against your own headphones in the source comparison tool.