What are some good techniques to produce good-sounding chords through the DMC channel?
Are you looking for looped or one-shot chord samples? What kind of mapper are you using (that is, is $C000-$DFFF bankable)?
Since getting a full range of a few octaves will take 5 samples of each chord type, I guess what would help would be having all those available to try out, but in the end only including the few samples that sound good. Since it probably won't all fit in the usual 16kB.