I don't know your soundcard but there should be no problems at all. Go to a pro-audio dealer and buy two of the most expensive balanced jack ( same as a stereo jack) to XLR leads. This should cost somewhere around $20.
Check that the plugs are either made by Switchcraft or Neutrik and you can't go wrong. Do not go to a HiFi dealer, I've tried and they quoted me GBP200 (ca. $300)
for the SAME XLR to mono jack convertor that cost GBP5.99 at a pro shop!!! You might find a switch on the back of the monitors which adjusts the sensitivity from -4dBu to +10dBV set it to +10dBV. -4dBu is the reference used for unbalanced connections (0dB equals 1V) whilst +10dBV is the balanced reference (0dB equals 2.83V). It might just be marked bal. and unbal. though.
As for the volume control: if you are using the card for recording your own music you probably will need a small analog mixer anyway for monitoring and to connect a compressor.
Check that the plugs are either made by Switchcraft or Neutrik and you can't go wrong. Do not go to a HiFi dealer, I've tried and they quoted me GBP200 (ca. $300)
for the SAME XLR to mono jack convertor that cost GBP5.99 at a pro shop!!! You might find a switch on the back of the monitors which adjusts the sensitivity from -4dBu to +10dBV set it to +10dBV. -4dBu is the reference used for unbalanced connections (0dB equals 1V) whilst +10dBV is the balanced reference (0dB equals 2.83V). It might just be marked bal. and unbal. though.
As for the volume control: if you are using the card for recording your own music you probably will need a small analog mixer anyway for monitoring and to connect a compressor.