Would an Isolation TT platform further improve my TT?

The problem for two stacked iso (spring) systems is they will interfere if the Fr resonant frequencies are close to each other. My Nirvana 2 stage isolation base has two stacked heavy mass-on-spring layers, where the Fr for each stage is predetermined to not be close enough to interfere. The lower layer of springs supports a much higher load than the top layer of springs. If two spring systems are arbitrarily stacked it will be like a car going down the road with two shock absorbers per wheel. It would not be smoother, it would be very bumpy.

I have always found that the more rigid the support, the tighter, more incisive and clearer the sound. Damping of the support by using wood or "absorbers" softens the sound. Marble and glass sounds etched while oak sounds warm etc. I'm old school and have to be convinced otherwise but spikes, cones and inertia allow the table to be as fixed as possible.

This^^^

Which is why I built this.
http://www.theanalogdept.com/images/spp6_pics/C_miller_web/TTstand_1.jpg

Which all I know for sure is it was a big improvement over the floor.

The best isolation occurs when there is a great ease of motion. Therefore, ironically and perhaps counter-intuitively, a flimsy and flexible stand would sound better than a rigid one. A rigid frame actually transfers vibration more efficiently than a rickety frame.

Would you put performing musicians on active isolation platforms too ? Remember, seismic activity, traffic etc.
Only passive isolation, my friends, active will introduce subtractive colorations - often the worst kind of colorations.

@inna that is a nonsensical comparison. The task of a stylus retracing the groove is to all intents exactly the same as a microscope or scientific instrument and hence solutions that work for the latter will assist the former. This is one area at least where there is hard and obvious science and designers like Mark Dohman have integrated these approaches into their tables

you are right regarding subtraction however, for example subtraction of motor noise, as you can clearly see in the traces posted in my system ... 😉

and Geoff while I agree in principle I should warn that if you are thinking of using an active or spring based approach a rigid support is the way to go, lest the problem of conflicting spring Fr you referred to, or potentially (in the case of a Herzan) even feedback!