I've used both Herbie's and the orange silicone o-rings; both were an improvement over no dampers, but I could tell no difference between the two. Of course, that could mean my system isn't resolving enough, or that none of my tubes were microphonic enough to benefit from any advantage the Herbie's might have. One thing was clear to me; from a cost/benefit standpoint, the orange silicone o-rings are hard to beat.
David
David