"Hiss" noise is something I usually associate with a driver issue. Driver, settings, and PC processing issues usually incur click, pops and or audio drop outs, but these can usually be addressed by defaulting a few basic settings. "distorted", slow or fast audio can be incurred by Sampling Rate mismatches. Google it, but I don't think this is your problem.
I suggest you simplify your rig for the sake of trouble shooting the issue. Disconnect everything. Connect ONLY the AudioBox 1818 to your computer. Change the default device for Windows Playback Devices to the AudioBox 1818 Line Out 1/2. Run iTunes or YouTube and playback. This basic audio playback from your computer should sound OK. If not, check settings and other PC optimizations. Open the AudioBox VSL mixer. Click Setup. Default the settings.
Un mute and Un solo all channels.
Connect ONLY 1 known good microphone to input channel 1. Using the VSL mixer to hear and monitor your input signal, do you hear noise? How high is the level/gain dial set for channel 1? 1'o'clock, 2, 3, more, when you hear the noise?
Disconnect mic from input 1 and connect to input 2, 3, etc... repeat tests. Do you hear noise on all channels or only 1?
If you hear "excessive" noise on any 1 channel or even all of them using ONLY the VSL for monitoring, then perhaps the AudioBox is faulty. Test with another microphone and mic cable to be sure.
Can you record the noise? If so, record and send a small clip to Tech Support in a ticket. This will help us determine if you issue is hardware of software related.