Vernon,
I am a Yamaha dealer in southern California and I am very familiar with the PSR 340. The sound engine is the same as the PSR270, which is a general midi set up not the XG sound set found in the PSR540,640 and 740. However, for the price, the sounds are very good and the effects are also very good. You will notice that the panel voices are better than the GM voices and this is because they have given these sounds more effects and attention. The GM voices have to sound similar to all the other brands of keyboards. The disk drive is also a nice feature if you like to play songs, or if you like to record songs and have a place to store them. I have to admit, I don't know what an MU10 is. I know what an MU5 and newer MU15 is, but I don't know what an MU10 is. If it is a tone generator, you can hook it up with just one midi cable from the PSR 340 midi out to the MU's midi in, then play the sounds in the module or have the styles play the sounds in the module. I hope this helps. You can give me more info on the MU10 and maybe my memory will get jogged enough to remember this one.
George Kaye
Kaye's Music Scene
Reseda, Ca.
818-881-5566
_________________________
George Kaye
Kaye's Music Scene (Closed after 51 years)
West Hills, California
(Retired 2021)