A bit late to the thread but here goes...
Experimented with RG142 and RG400 coaxial in place of the Dart original one. Physically both are the same diameter, roughly twice that of the original Dart one. Visually they all look the same, with a handsome tan FEP outer sleeve.
The RG142 has a...
Got my NHB-108 on two 3" engineered wood slabs sitting on inverted cones isolated by a ball bearing.
Dartzeel doesn't seem to want or need such things, says so in one of the manuals that they are already equipped with isolating feet.
YMMV, of course.