No sound coming out from my vs700 R

It is a frustrating problem that I have on some heavy projects or some VSTs like chamber strings from spitfire audio. I think it might be a driver issue because when I change it from ASIO to WMD, sound comes back. I don't like to work with WMD because compare to ASIO it is a bit slower and I prefer to stick with ASIO. I am just wondering is there any buddy here has the same issue? Is there any solution? 
Do you think I should sell my vs700 and buy an RME?

Thanks, Ken.
when I increase the buffer on Kontakt, sonar won't play anything just meters are going up and down. I realized Kontakt should be on around 60 for DFD and buffer on sonar must be more than 512 so in this case, randomly sonar will play sound but the problem is some of my Kontakts like string chamber will play with glitching and cracking.
when I switch from ASIO to WDM everything back to normal and no glitching and cracking. I think there is a problem with VS 700 driver and Kontakt. I heard octa-capture had the same problem and they fixed it but because unfortunately VS 700 discontinued, there is no support for it. 
By the way, which model of RME do you recommend? which one quality wise compete with apogee symphony?

RME interfaces are all good and return very similar quality and latency.

It's a matter of working out how many inputs and outputs you need and whether USB or Thunderbolt and picking one (or more, RME's ASIO drovers allow multiple units to be used at the same time) that has what you need. USB is fine for most applications that don't require recording lots of microphones and hardware synths at the same time.


I prefer USB. I see new models which ufx and ufx+ . Do you know if these models compete with apogee symphony?(quality wise)