I used a drum sander attachment ($8 Harbor Freight)
for a drill to remove 3 of the 6 rings around the soundhole.
This has livened up the tone considerably, especially down
at the bass area. The sound hole is definitely too small.
If you wanted to avoid a lot of bass down around the A and B
notes, you might just remove 1 ring. Have all sanding going
downward to avoid lifting the finish. Do the last ring by hand
rounding the edge there. I probably will switch to a 34 gauge
on the A to cut the bass back. I haven't found a stain to match.
I am curious as to how the GJ 10 compares to the better ones after doing this.