Now I'm a believer too...
On the advice of the above posters decided to try Herbie's Threaded Stud Gliders and damned if they don't work.
Installation showed me that the DIs can become very dusty in a month and that the pointy feet don't work at all on a hard wood tile surface. The gliders are a much better way to level and secure the speaker and, especially, to make fine spacing adjustments afterwards. Went with the inch and a half thread in order to raise the speaker just a little and found the tightening nuts essential to get a nice stable result.
Immediately tried out known bass examples to see if there was any change -- like to use Flight of the Cosmic Hippo (Fleck) and Tarnation (Thile and Meyer). The bass was less ringing and more realistic. Interestingly, it was possible to turn the volume up a little with this added tautness in place. Then tried Mahler's 6th with its opening double bass punctuations. Here too, the bass lines were better separated and more realistic.
SO thanks to those above who put me onto these gliders; your knowledge and information is one of the ways that these threads work. Haven't found this kind of low cost improvement since I discovered Blue Jeans Cable and their Belden 1800f cable a number of years ago.
BTW, took the precaution of getting some replacement speakers for the DIs (I blow woofers and tweeters every now and then...) and they came this week. Uniformly high quality speakers and it is a big plus for me to be able to order replacements on the open market at the most competitive price. Don't let anyone lead you to believe these are "cheap" speakers. If you order a complete set at the best Internet price it will cost you around $1200. A couple of woofers and tweeters are around $200.
