Hi Chris,
very nice music! I am thinking the reason the cello may not be standing out as much could be that, it appears to me that there is another instrument doubling the cello line [is it an oboe?], either in the same register or an octave above. By either taking it out, or lowering it's volume, maybe that could solve it, and I am also wondering if there are other instruments accompanying it with harmony in the same note range of the cello melody. If they are, maybe putting the harmonic background lower than the cello, or maybe above it, could help?
Also, when I listened to John Williams "Shindlers List" music where the strings provided harmonic background to a solo violin, I was wondering how on earth he got the solo violin to stand out over the strings so well - the problem being that having a string solo instrument with a string background, it could be hard to have the solo violin stand out over a timbre that is similar. When I found the orchestral score to this in one of the music libraries here, I discovered that he has the string section play con sordini. I don't know if you have any muted string samples, but maybe that could also help the cello solo stand out also.above the string background. If not, maybe a nice woodwind sustained background could also be a possibilty.
Hope that may be helpful! By the way, as I said, it is a very nice melody. I hope we get to hear the rest of it!
best regards,
Steve[:D]