Baby Booties or Big Baby Booties should do very well under the DAC power supply. They would do very well under the DAC also if the DAC were sitting on the shelf or dedicated shelf. You don't want to use one rack component as damper for another, though. The player will induce all kinds of vibrational distortion into the DAC and vice versa. A dedicated shelf is always best, though components sharing a shelf laterally is usually okay, especially if each of the components is isolated with Booties or Tenderfeet. Something like a SuperSonic Stabilizer on top of a component is perfect for damping, working hand-in hand with the isolation feet under the component.
Sometimes because of space restrictions it's necessary to stack components. If so, placing Tenderfoot isolation feet between the components is the best thing you can do. TenderSoft Tenderfeet between DAC and DVD player should provide adequate isolation--and use four Tenderfeet under the DVD player also, not Booties. With Tenderfeet underneath, the DAC's additional mass might very well provide a vibration-damping function, but this should be a by-product of stacking by necessity and not by design. In many cases, trial-and-audition is the only way to know for sure.
IsoBalls would likely do very well under the sub, though they're not recommended for this application. Four Big Fat Dots would be my recommendation, compatible with our website's product descriptions and recommendations (Giant Fat Dots or Giant Fat Gliders would also be very good choices, giving you even more vibration absorbing-and-blocking "beef" for the job, more footfall/macro control. In most cases, regular Big Fat Dots should be more than sufficient, though, for a sub that's not too big like yours.
Several options would do very well with the speaker stands. Simply placing three Square Fat Dots or Big Fat Dots under each would be ideal sonically. For the sonic benefit plus easy mobility, three Little Fat Gliders w/adhesive or three Giant Fat Gliders (no adhesive needed) under each stand would be superb. If you want to keep a lower profile, regular "Thin" Fat Dots would do very well, though they might not provide quite the sonic benefit as thicker Fat Dots.
Herbie's Audio Lab