This afternoon, I finally got around to performing the snare mod on my Volca Beats.
There are two circuit boards in the Beats. On the board with all the knobs, between the Hat Grain knob and the closest IC, there are a couple unused pads labeled "C78", where an embedded capacitor was (presumably) supposed to go. The absence of this capacitor gives the Beats its notoriously-awful distorted snare sound.
I soldered a 104 (0.1uF) ceramic capacitor across the C78 pads, and it really makes a nice difference. From my experience, there are some important notes:
(1) Korg packed these things in at damn close quarters, so you need to have pretty steady hands and good eyes. In five years, I probably won't be able to perform this sort of mod, unless I really luck out and beat the age-related visual acuity odds.
(2) You should use a low-wattage soldering iron and a precise conical tip. I used a 25W Weller WP25, but a 15W iron might be more appropriate.
(3) Watch the nearby knobs! I managed to slightly melt my Hat Grain knob with the iron's shaft. It's easier to attack it from that side than from the IC side, but you do want to be careful.
For my time and money, I think doing the mod was worth a minor melting mishap. The snare has a nice snap to it now, the decay control is usable, and the instrument probably sounds more like it was designed to sound.