I don't know about mid-1990's vs. today, but, it is not necessarily the case that newer stuff beats older. First, the simple, and I suppose one could say primitive, technology of the Audionote and Zanden approach delivers fantastic results. I would take the oldest DAC-5 over just about any other current non-Audionote DAC out there now.
The other issue has to do with current chipsets and transports. Aside from a few companies that make proprietary transports and D-A and filter chips, manufacturers have to rely on what big makers of OEM parts offer to the market. D-A chips, in particular, serve a variety of functions, so many new chips are designed to serve multiple function, and are not necessarily issued because they are superior in performance.
Some premium manufacturers, like Naim and Zanden, have horded "old" no longer manufactured chipsets, because, in their view, they offer superior performance. Examples would be the Burr-Brown 1704 chip. So, it is possible that a newer model from a particular manufacturer will have inferior sound to a prior model because a superior component is no longer on the market.
The other issue has to do with current chipsets and transports. Aside from a few companies that make proprietary transports and D-A and filter chips, manufacturers have to rely on what big makers of OEM parts offer to the market. D-A chips, in particular, serve a variety of functions, so many new chips are designed to serve multiple function, and are not necessarily issued because they are superior in performance.
Some premium manufacturers, like Naim and Zanden, have horded "old" no longer manufactured chipsets, because, in their view, they offer superior performance. Examples would be the Burr-Brown 1704 chip. So, it is possible that a newer model from a particular manufacturer will have inferior sound to a prior model because a superior component is no longer on the market.