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I used to sing in a '50's/'60's show and occasionally I would sing something that needed to be doubled. That was a popular effect back then. For those who don't know, that takes recording a part on one track and then recording it again - as close as possible to the first track - and then combining them. The timing and pitch of the two tracks will vary and the result will be fuller.
There really was no way to do that in a live performance. I had tried and didn't like chorus effects. I wound up using an effect by TC Electronics called Voicetone D1 which worked quite well.
Where I'm going with this is that I just tried it with my fiddle and - wow - what a sound. I can sound like 2, or even 4, fiddles. I'm using a mic with a low-Z XLR connector but it could be used with a pickup and a DI. Mine is about 5 years old so I don't even know if these are made anymore.