Mass loading Tannoy Definition DC10a speaker.

Thank you for your input. Possibly tighten the bass and make it deeper.  In general I am trying to get it to the next level, if applicable. I am happy with the way it sounds now. 

Mulveling, my experience with the DC10a is that it is balanced and warm top to bottom when I am not using the spike(just let them rest on carpet), I have very detailed bass, every note is there and it rattles the floor (in a good way I mean). Bass is full but the very deep bass(<40 hz is not that impactful but you hear the note clearly). Overall, it is a very visceral experience. When I put them on the spikes, the sound is a bit more detailed, and may lean towards being bright but not much. They sounded best with isoacoustics isopucks underneath them. 

I previously owned a Rel Gibraltar 2, and the deep bass was very deep-the thump- ( I know I am not comparing apples to apples here, but just to make my point)

Bolong, I totally understand, and this is my concern. It may be too much of a good thing, that is why I started this thread. The other concern, if I don’t like it, it is very hard to get the sand (or anything else) out, since the opening is about 2 inches and the box is bigger, there will be some residual sand there. If it is lead shots or atakama atabites, if may be easier to drain. I can’t shake a 100+ lbs speaker (like a salt shaker)  to get the sand out of the circular 2-inch port J

The other issue is that I liked the isopucks and I may buy GAIA II which support up to 120 lbs speakers. If I load beyond 120 lbs, then the GAIA IIs will be useless, and I have wasted $600.

Maybe I can start gradual mass loading, 2 pounds at time, and see where the sweat spot is. If I exceed and want to go back, I have pull back to the previous weight (sweet spot) and leave it there. I was hoping for someone to tell me this weight, so I don’t have to guess nor do this experiment. Tannoy has R & D and they should have provided some guidance rather than an empty compartment and a few lines in the manual about mass loading.

Thanks again

Thank you so much Slaw, This Is a brilliant idea. I can even use multiple small

size bags in increments so they are easier to get of the access port. Thanks 

Thank you for for the excellent suggestions. 
component:

power supply : dedicated 20 AMP line>shuntaya 20 amp power cord > Furman elite 20 amp > out of the high power non filtered outlet comes out synergistic research atmosphere sx excite feeding a power cell 8. All hear  is supplied by this power cell.

 Power cords: Ansuz acoustics A2 to all components 

front end: Eversolo dmp- dmp10, Ethernet AQ cinnamon 

premaplifer : PA audio BHK signature preamplifier ( stock 12AU7 tube)

amplifier : Cary adio 200.2 ES

interconnects : from Eversolo to preamp = audience studio one Xlr , from preamp to amp= Kubala- Sosna Emotion Xlr , from amplifier to speakers = Kubala- Sosna Emortion speaker cables , KS  jumpers  for highs in the DC10a

Thanks  for asking