was there crackling sounds previously? i'm using the toneport GX version with a macbook pro. when there's instances of crackling, i'll unplug the toneport and restart my mac, and the crackling will go away. there's crackling usually after i've left the toneport plugged-in until the mac goes to sleep..
I have to agree with you, it is the LATENCY plus your sound card on your mainboard (although the toneport can be considered also as a soundcard)
what you need to do is to find a suitable latency for your pc..next try to put the toneport as your DEFAULT sound egine/soundcard whatsoever...possible update drivers this and that..