Hello Raul ..........
I have had both the AT-616 and EquaRacks on the 5000 and I would give the nod to the EquaRack, although the AT-616's are very good and clearly superior to cone type devices.
Nevertheless, experimentation to date a DIY has a compression spring base in the lead position for the most effective isolation system. I a hoping that the machina dynamica spring system will give a benchmark comparison.
I am a firm believer that effective isolation of the RX-5000 is very important as there are lots of inherent internal resonances from the chassis, platter and arm board interfaces. They must have an impact on sound - as does the wood and resins used in a violin define its tone n'est pas?
Steve