For turntables isolation is critical for everything else it is not. Just a waste of money.Sorry but for speakers it is more than very important..... My experience.....
The impactful results of resonance/vibration controls embeddings is very audible....The problem is the way to reach results is a complex problem...
I solve it myself for my speakers with sandwich of multi layered materials but it was, unbeknownst to me at first, unsufficient and not completely positive, then i added a damping loaded fine-tuned double set of springs boxes with asymmetrical fine-tuned compressing force for those under the speakers and for an another set under the load on top of the speakers...That gives astounding positive results on ALL counts not only between bass and high frequencies but for timbre accurate perception and imaging....The dissymetry between compressing force and the fine tuning of the load are CRUX of the matter....One set of springs boxes were not sufficient for me, it takes 2 sets for optimal spectacular results.... But it worked....
Saying other wise and vouching that vibrations/resonance embeddings controls is without interest and a waste of money reveal a lack of listening experiments ....I will concede tough that many branded products are probably only partially effective at best, for example the set of springs boxes under the speakers were not totally successful positive controls like it seems at first, it takes for me a double sets to reach naturalness of timbre, one set cannot do it because internal resonance of the speakers are too powerful with their negative impact but their power was decreased with a dissymetrical compressing force on the 2 sets of springs... But with a double sets it was spectacular indeed....Fine tuning the compressing load was very important and is very important even for one set of box springs....Then the easy solutions are perhaps difficult to reach...But the controls of vibrations with speakers is very important and not only for turntable where it is evident....My speakers are near my other electronic components on the same desk then particularly important for me to solve this problem...
My best to you and to all....
