@mewsickbuff, I can help ya’ll. Not that I want the credit, but it may have been I who brought Ingress Engineering to the attention of Audiogoners a few years back. I had read Barry Diament’s writings on the subject of isolation, and found his argument persuasive. So I bought myself a couple of sets of the Symposium Acoustics’ Roller Block Jr’s. They are a fine product (as are all of SA’s), but I couldn’t help noticing that the design of the Jr. was quite a bit different than Barry’s Hip Joint design. In contrast, the much higher priced "original" Roller Block did adhere to Barry’s idea of a single cup and ball bearing.
So I did some more investigating, and came upon a forum upon which Barry’s ideas were being discussed. I was not alone in my quest for perfection! A group of DIY’ers had come to the attention of Michael of Ingress Engineering. He was making what was essentially a knock-off of the Symposium Jr. (no offence Michael ;-), and selling his version for about half the price of the Symposium. The only difference I could see was the Ingress wasn’t anodized black, being just natural aluminum. The Ingress was about 1.5" in diameter to the Symposium’s 1.875", no big deal. The diameter of the bowl appeared to be identical, so I ordered some. Sure enough, the two were essentially the same. They were both made of 6061 aluminum, and polished smooth. Since the Ingress is non-anodized, you can see your reflection in the bowl!
But being perfectionists, forum members pointed out to Michael that Barry’s Hip Joint design called for a much larger bowl to be carved into the cup. The larger the bowl, the shallower the incline the ball bearing must climb when confronted with vibration (the basic idea of roller bearing isolation), and the lower the resonant frequency and greater isolation does the roller bearing provide. Barry’s design also was just a single cup with a ball bearing, not the cup-over-a-cup design of both the Symposium Jr. and the Ingress. To his credit, Michael went to work and created a second model, one just as Barry Diament had described and machined locally for himself.
The second model was a single cup, with a bowl of much larger diameter carved into the cup. The cup was machined out of the harder 7075 aluminum, and polished to a finer degree. Now we’re talkin’! I got myself a set of those, and man are they great! At the time Michael was selling the new model for just a little more than the original; only one cup cut down on cost, but the 7075 aluminum cost more, as does the time and effort expended polishing the bowl to a smoother, more friction-free finish.
Now having all the roller bearings I needed for my system, I stopped paying attention. Your post lead me back to the Ingress Engineering website, and I see Michael is currently offering two models (plus a larger one for loudspeakers), the improved one now called Mk.2, an even newer one MK.3. Both are single cup of the same size, both machined out of 7075 aluminum, and both have the same size bowl. The cheaper one is anodized black, so I’m assuming the pricier one has been polished smoother, but that’s just a guess. I have no apprehension in recommending either, or both! Buy a set of each, and compare them for yourself. You may end up with the pricier one under your source component, the cheaper under your pre-amp.
I'll beat Geoff Kait to the punch by pointing out that the roller bearing provides isolation in all planes but the vertical. In the vertical, it acts a coupler, not an isolator. To get isolation in that plane, you must look elsewhere. Geoff just happens to sell cute little springs which will do that for you ;-).