The 80 ohm draws more power than 240 ohms...
you will need to turn it louder with the 240 ohm because 240 draws less power. Maybe 240 still won't be loud enough?
Oh I see, the 240 is made for hooking 4 pairs to one power amp...probably.
Probably right, the 240 may need a power amplifier. How many watts output is a sound card? Not much. It's more like a line out than a headphone out.