Hi Yurika,
The best card we've found for now is the HT Omega Fenix. It has a clean frequency response from 20-80kHz, high enough output voltage to trigger the state machine directly (ch3+4 send a 1ms sync pulse at sound onset), and 10+/-1.5ms latency using the latest PsychToolbox + WASAPI drivers. The 'develop' branch of the Bpod_Gen2 repository already supports this card.
FYI It's not documented yet, but the develop branch also has PsychToolboxAudio - a more cleanly written class to wrap PsychToolbox's PsychPortAudio (example protocol here). PsychToolboxSoundServer will still be supported, for compatability with old protocols.
I hope this helps!
-Josh