I've always had trouble trying to quantize drum tracks after splitting at transients in Reaper because the "Extend item to overlap earlier item by x milliseconds" and the "Shorten earlier items if quantized items overlap by more than x milliseconds" options never seemed to behave as expected. The short of it is that very often I would experience Reaper quantizing my hits but certain automatic crossfades were placed right over my transients completely killing them and making for a lot of irritating manual fixing. After EXTENSIVE playing around and analysis, I finally figured out the exact mechanics of how those functions operate and why it doesn't result in the behavior that you would expect at first. I'm not going to get into the details, but this is how you avoid those transient killing crossfades and have Reaper place the crossfades at the actual points you want it to (ie. as close to the beginning of each hit as it can without having the next transient being redrawn as part of the previous item)... Split all your tracks at say the snare hits (either via dynamic split or tab to transient and manual split) Select all items, right click>item processing>quantize DON'T check off the "Extend starts..." box Check off the "Shorten earlier..." box but set the value to ZERO ms Now all your hits are quantized with no overlaps or dumb crossfades, however, you will have some gaps and also some parts where hits that were late are now shifted early so 2 items will be right next to each other with no crossfade which will cause audio glitches... This is where the cleverness occurs! While everything is still selected, quantize AGAIN Check off "Extend starts..." and set the value to whatever is appropriate, I usually use like 10ms, this will be the length of your crossfade Check off "Shorten earlier..." and set it to the same value as the "Extend starts..." field Now all the gaps will be filled in by Reaper automatically extending the start of each item backwards and adding an auto crossfade of the specified length to make sure the transition is transparent and all of the parts where two items were right next to each other with no crossfade will have a crossfade of the specified length placed immediately before the transient. I was SO stoked when I finally got this working the way I wanted it to today, Beat Detective eat your heart out!