I'm having great luck with the N.I. Komplete Audio 6,and I can easily track with Guitar sim's,and other plugins at 32 samples @ 48KHz with W7 64,SONAR X2 64 @ 8ms Round Trip Latency with a Dell xps 2011 model i7 2630qm cpu.
[not brilliant,but this is an 18 month old $999[[less in the US!] laptop,and I 'd rather have 8ms and solid than 4 and "wait and see "what happens today"]and remember many if not most don't report AD/DA,this RTL is tested with thisRTL Utility | Oblique Audio
Driver 3.0.3 totally solid,and I tracked a song using both mic pre in's at once,no problem,though you need a good USB 2.0 port[mine has 2xusb3.0 + 1x usb2.0/eSATA port-thats the one I use.]
You should always use the latency checker[DPC latency] a "High performance" power plan,and have ALL usb power saving junk turned off,and you'll be good to go.