Tried it both ways!
I have two usb devices that I've used here, one is a Behringer uca200 interface that provides both stereo input and output channels thru RCA plugs, the other is a simple 1/4" to usb input only "guitar cord." When my q301la is running Realtek in "original" mode, I can plug these in and start playing (pnp) but with delay, probably 240 ms or more, not bad it your listening to videos or stuff but unusable for playing an instrument using audio feedback. What I do like about this is that it allows use of the existing Realtek audio so I'm able to bluetooth (or use the headphone jack) to speakers, and the software amp simulators, when used, behave very well. When I do this with ASIO4ALL drivers and makes some minor adjustments to the buffer and stuff, it perks-up really well and is usable as a direct feedback while playing. The problem is that I can't then use the ASUS's audio output and must plug in the Behringer and use its usb output, which is okay but requires cabling. Also, the amp simulators don't behave as well with the ASIO and sometimes freeze-up if I switch into and out of ASIO to makes adjustments. I figure if the usb interfaces were the cause of the delay it would manifest itself with either driver. Also, when watching the bar graph in the control panel while adjusting the input level (which is using Realtek?), the graph moves faster than the output, telling me the delay is at the Realtek side.
