What USB sound card to use for frequency measurement?

Hi,

I was using Behringer UCA222 for frequency measurement, but recently learnt that it has poor channel separation. I verified by using a signal on left channel and connecting and amlifier/speaker on the right channel. I could hear the test signal from right channel:confused:, even though it was faint.

So, what better USB sound card do you guys suggest for frequency measurement?

Thanks in advance,
Warm Regards,
WA