Short answer
Both are audio interfaces, both at $199.
The Universal Audio Volt 2 reaches 100 dB on 558 of the 567 models here, the Tascam US-2x2HR on 541.
| Specification | Tascam US-2x2HR | Universal Audio Volt 2 |
|---|---|---|
| Power into 32Ω | 18 mW | 84 mW |
| Power into 150Ω | 17 mW | 28 mW |
| Power into 300Ω | 12 mW | 22 mW |
| Power into 600Ω | 7.3 mW | 12 mW |
| Output impedance | 66 Ω | not published |
| Output noise | not published | not published |
| Price | $199 | $199 |
| Headphones it reaches 100 dB on out of 567 | 541 | 558 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Load | Tascam US-2x2HR | Universal Audio Volt 2 |
|---|---|---|
| 32 Ω | Published | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Derived | Published |
| 600 Ω | Derived | Published |
Both makers publish a power rating. Tascam US-2x2HR publishes at 32 Ω; Universal Audio Volt 2 at 32 Ω, at 300 Ω and at 600 Ω. The other rows are worked out from those.
So the two columns are not equally firm row by row: at 300 Ω and at 600 Ω only the Universal Audio Volt 2 figure is the maker’s own. On those rows the derived number is the one to doubt first.
17 headphones reach 100 dB on the Universal Audio Volt 2 but not on the Tascam US-2x2HR — Abyss AB-1266 Phi TC, Audeze LCD-5, Dan Clark Audio AEON 2 Closed, 14 more.
541 of the 567 models here reach 100 dB on both.
Headroom is at a 100 dB SPL peak.
The widest gap on the list is the HiFiMAN HE400se: Universal Audio Volt 2 has +9 dB of headroom there against +2 dB. 7 dB is about 4.7 times the power, which matters for peaks rather than for how loud the music sits.
The hiss columns are empty for Tascam US-2x2HR and Universal Audio Volt 2 because neither maker publishes no output noise figure.
| Headphone | Impedance | Needs | Tascam US-2x2HR headroom | Universal Audio Volt 2 headroom | Tascam US-2x2HR hiss | Universal Audio Volt 2 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +21 dB damping | +28 dB | not published | not published |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +1 dB damping | +8 dB | not published | not published |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +13 dB damping | +18 dB | not published | not published |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +13 dB damping | +16 dB | not published | not published |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +2 dB damping | +9 dB | not published | not published |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +7 dB damping | +10 dB | not published | not published |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +3 dB damping | +5 dB | not published | not published |
| HiFiMAN Susvara | 60 Ω | 50 mW | -5 dB damping | +0 dB | not published | not published |
These two cost the same, $199, so price settles nothing. Out of the 567 models here, the Universal Audio Volt 2 drives 17 models to 100 dB — and on the other side there is no such advantage at all.
Only published figures count here; blank axes are counted separately.
Each in full: Tascam US-2x2HR and Universal Audio Volt 2.