Sand bags under a cdp - didn't work well

Tube people to maximize benefits of inner tube under CDP, be sure and use torpedo level and make sure CDP is level when sitting on inner tube. If you put dampening weight on top, just shift it around by hand to get perfect level. For tube alone it may have to be located off center under CDP to get perfect level. For a small DAC unit I would go with vibrapods if you want to use sonething to make sound fuller/richer.

With so many positive reports I had to give the tube a try. Picked up a couple of 6"x4" wheel barrow tubes. Almost perfect size for my CAL Alpha and Delta. After one evening of trying various combinations:

The Alpha tube DAC sounds better on the BDR points than a tube. There was a very minor loss in resolution with it sitting on the tube. That there was little change is no surprise as that was the case with the BDRs. They improved the sound slightly, adding just a bit of resolution and slightly darker background. Also tried a tube/hardwood/BDR/Alpha sandwich. No discernable difference from the DAC on the points alone.

The Delta transport was another story. On the tube alone the sound was noticeably fuller and more musical, though a bit soft at the extremes. Putting it on a sandwich of tube/hardwood/BDR/Delta seems to give the best of all worlds. Want to load the chassis, but lacked space due to closeness of self above. Suspect this would further improve things as that was the case with the BDRs alone.

Will certainly want to listen to this longer, as well as let everything settle in as I had to disconnect and move a couple of components to make room for the tubes. Also want to try sand bagging the transport, too.

Price of this tweak was less than $25 including the hardwood board (actually a cutting board) and wheel barrow tube.

I posted elsewhere that the tube I tried did nothing at all but now I see from some other posts that it wasn't wide enough. Too much air, not enough squish? The urethane mat is still sounding good, you can get one anywhere that sells woodworking tools or possibly the non-skid mats that go under area rugs. Anybody in the fastener business know where i could get urethane washers to go between the mdf and the washers I'm using on the threaded rod equipment rack? Already tried Depot and Lowe's, nada.

Yet another follow up in this saga. Now have the Delta on the tube alone with a bag of lead shot on the top. It really needs the the chassis loaded because the case rings like a bell. The space constraints didn't allow this with the multi-layer set up described above. The shot bag has a side benefit in that it also allows for convenient leveling of the transport.

The extra cones are now under the preamp. While we were listening one day I slid the cones into position. Everything was left on during the precess and the change was immediately noticeable to both sets of ears in attendance. The annoying sibilance previously attributed to digital glare, room acoustics (slap echo) and other whine du jours was suddenly almost (but not quite) completely gone, replaced by a greater sense of AIR. Much better resolving and most lucious!
Let me add that by far this site has helped in my audio journey more than every other source of information combined. Thanks again to you all for all the myriad suggestions and brain storming.

I've replaced my wheel-barrow inner tube with a Neuance shelf. Bass is better controlled. Treble is perhaps more detailed and cleaner. I found that sticking a couple of sheets of self-stick asphalt (unpeel it from the trunk of your car!) on the CDP lid is easier, more stable on an air bladder, and takes much less space than mass-loading. Ernie