When I play my electric guitar through my Tascam US144 into Reaper the clean sound from the pickups is recorded. I hear this clean sound in my headphones as I play. I have worked out how to apply an fx to this. I can then play the recorded track back with a variety of effects. However I can't work out how to hear the fx being applied to my guitar playing as I play. I can only ever hear the clean signal from the guitar while playing. How do I apply the fx to the sound I hear while I play? Being able to hear the effect of the fx in real time changes the way you play, eg palm muting. Being able to hear the effect of the fx in real time also helps with tweaking the fx settings before actually recording anything. Thanks.

You have to turn off the direct monitoring of the input on your Tascam. I went through the manual and it seems there is no specific option for this in the driver control app. So it might be as simple as turning the "Mon Mix" knob all the way to "Computer". Then you have to turn on the input monitor in Reaper (the little speaker symbol, should be white) and that's it (I guess).

I'm pretty sure the US-144 is 95% the same as the US-122, in which case there's a switch to turn Direct Monitor off.

Thanks for the tips, I will try them out. The US144 is pretty much the same as the US122. I'm not sure how to determine its latency.