Comment 6 for bug 1430464

As discussed in https://github.com/mixxxdj/mixxx/pull/1254#issuecomment-346853954 , external software effects would be supported much better by implementing support for plugin formats designed for this purpose such as LV2 (Bug #1530238) and VST (Bug #1740335). We cannot use Mixxx's controller mapping system to interface with separate programs in a reliable and intuitive way, but we can do that with effect plugins.

As for send/return loops with hardware effects, that is not technically possible because our effect units have switchable inputs and a hardware send/return loop introduces more latency. The extra latency could only be compensated for to keep all channels aligned if the signal path was fixed. Switching the latency of a signal path during playback would create brief gaps of silence and the signal path with added latency would be misaligned in time with the other channels.