Many of the replacement parts, and the upgrade paths are now gone for the HW-19. You "Might" be able to get things like On-Off Switches, the Hurst Motor, or a SAMA if they're not on backorder. AFAIK, the Sorbothane Pucks are no longer available, and don't pop up much anymore. Thier availability used began to wane many years ago. It's been a good two years now that the HW-18 has been discontinued.
Of course, the two largest, and most influencial upgrade components to your system I feel, will be the Cartridge, and the Phono Stage.
Say as an example, you're using something like a EAR 834P, PS Audio GCPH, or other $800-$1500 Phono Stage, and now step up to a $3K-$6K Stage, let's say the Modwright, Aesthetix Rhea, or such, the differences will be substantial.
Sounds to me that you have taken many measures to insure good isolation, and as you know lowering noise floor is very important, regardless of what components are being used.
I cannot comment on the Koetsu Urushi, but as well, here a difference of sound would be noted with another brand no doubt.
As for Sorbothane Puck Height, I'm going to guess the the Pucks were 1-1/2" diameter, and about 2" tall. As I'ms sure you know, height will be important so that Plinth with sit correctly within Base, so you can re-install Motor Pulley Cover if you use it. With the SAMA of course, on can shim to adjust to correct height for Platter Belt. Rubber, or even Metal Shims could be added with the Sorbothane to add additional height if needed. Mark
Of course, the two largest, and most influencial upgrade components to your system I feel, will be the Cartridge, and the Phono Stage.
Say as an example, you're using something like a EAR 834P, PS Audio GCPH, or other $800-$1500 Phono Stage, and now step up to a $3K-$6K Stage, let's say the Modwright, Aesthetix Rhea, or such, the differences will be substantial.
Sounds to me that you have taken many measures to insure good isolation, and as you know lowering noise floor is very important, regardless of what components are being used.
I cannot comment on the Koetsu Urushi, but as well, here a difference of sound would be noted with another brand no doubt.
As for Sorbothane Puck Height, I'm going to guess the the Pucks were 1-1/2" diameter, and about 2" tall. As I'ms sure you know, height will be important so that Plinth with sit correctly within Base, so you can re-install Motor Pulley Cover if you use it. With the SAMA of course, on can shim to adjust to correct height for Platter Belt. Rubber, or even Metal Shims could be added with the Sorbothane to add additional height if needed. Mark