Aesthetix Calypso How many versions?

In my research, it seems there has only really been one change, which had to do with resistors. There were some noisy stock tubes reported for awhile, and that now seems fixed. There were also some hum problems reported with Ayre amps, but Ayre changed their grounding scheme and took care of that, I don't believe the Calypso changed anything with regards to the hum when used with Ayre. I would be interested to hear from anyone more knowledgeable on whether there were additional changes or versions, and maybe what serial number started the resistor change.

Does anybody know what is the benefit of ultra quiet resistors? Quieter background or less hum maybe? Probably Jim White can answer this better.

Probably the same mod I just did to my Aesthetix Io, swapping most of the Mills Military for Roederstein precision metal film resistors.

The Roederstein's are the standard now. Quieter, lower distortion and superior resolution.

Part of the upgrade on my Io was a slight correction in the RIAA curve. Obviously this would not apply to the Calypso as it is a line stage only.

Those with Io's more than one year old, be aware of this upgrade. It's extremely audible and very inexpensive.