Ed,
STOP ! Don'y buy a used 8000 ! ! !
You can get a NEW one for about $1700 in US.
Here's why you DON't want the 740 -
1) speakers are lousy - not loud at all
2) if you're playing the violin, can you get to the variations live? Maybe two are enough.
3) The harmonizer & mic input are terrible - You'll need an external amp, harmonizer, EQ, etc. With the 8000, it's one piece - that's all. Forget the 740. It's not in the major leagues.

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Uncle Dave