@hifiguys you received some very good advice from dover, as expected. As for the Micro gunmetal platters, they ring when not properly damped, so you do need a mat of some kind. Some might call the sound ‘lively’, but with the ‘naked’ platter the table tends to sound a little bright and unsettled.
Micro advertised at the time that the platter didn’t require a mat, but to my ears this clearly was a misdirection. The CU180 (and the heavier CU500) copper mats were sold as accessories, but really should have been an integral part of the table. In my experience this copper mat is the only one that effectively kills the ringing without killing the dynamics along with it (as most other mats do to some extend). Without it you won’t be able to hear what the RX-5000 can do.
dover is also correct to be very careful with used samples, but thankfully Micro-Seiki.nl offers exact one-on-one replicas that will be perfectly flat. Not cheap either, but these are quality products. Highly recommended!