Hah funny enough I found a review from amirm of my Soundblaster Z card and he basically said the DAC is good but the headphone amp is weak. Yet it sounds good to me. Maybe I just am not pushing them hard.
But in regards to your choices, I'm not familiar with any of these brands. The problem is that they can claim whatever they want for specs but we need people to review them to establish trust. But based on the websites, the specs are kinda all over the place.
HA400: approx. 40 mW in 100 Ω
Samson QH 4: 282mW per side / 564mW per channel, loaded 32Ω
Personus HP4: 130 mW/Ch., <0.5% THD+N, 60Ω load
It seems like you'd get the most power out of the Samson. But that's assuming a linear relationship between the power rating and nominal load impedance (it's not linear in reality). I'd probably get the Samson, hopefully with a easy return policy and try it out.