Does all files follow a specific format or can they suddenly contain diffrent information, like skipping the mono or not contain tr-808?
if all you need is to seperate the files with a decending number sequence this is quite simple.
Code:
x=0
for i in *; do
if [ $x -lt 100 ]; then
if [ $x -lt 10 ]; then
$number="00${x}"
else
$number="0${x}"
fi
fi
newfilename=$(echo "RolandTr-808#$number")
mv "$i" "$newfilename"
let x=x+1
done
This will work for quite alot of files, but will only add 0's up to 100, you can add more if's and stuff if you want but principly this is how it works.
If the files changes and needs to be designated something other then RolandTr-808 it's a whole new problem and I would say we need more information on how the files is named.
ps. the above script doesn't care what the file was named before, it will just be named as said above with a trailing number. ds.
ps2. I haven't tested this

I would recommend putting mv line in an echo "<line>" and dry-running this before doing it live

ds.
Best regards
Fredrik Eriksson