I find the MidiPlayer utility very useful for taking a lot of the hassle out of transferring midi-files onto my PSR3000, so I assume it will help with your 910.

This is on PSRTutorial site (as mentioned above) on this page http://psrtutorial.com/Help/UBedesem.html

Note that there is a batch conversion utility so once you get it set up to your satisfaction you convert everything at once!

Michael Bedesem deserve huge respect (as they say these days) for his utilities!

Also, assuming the PSR9xx has the same sort of internal processing as my PSR 3000, don't mix your midi file track levels too high; I usually have most tracks at volume level 70 (except for acoustic guitar which is usually too quiet!). The internal processing in my 3k tends to internally clip heavy bass signals if the midi file track levels are too high.

And finally - the megavoices can sound fabulous in midi files but they require a lot of manual tweaking, especially the distorted / overdrive guitar voices which put a lot of flexibility into a single patch but as a result can be very (politely now) challenging to get correct. Initially I'd just use the "Cool" or "Live" versions. The Yamaha MegaEnhancer utility can help here but sometimes it overdoes it.

Enjoy!