10-15 year old hi end DACs are still great.

“Vintage” DAC should not be a thing. Immature tech. 

Sorry but that statement is simply not true. Many vintage power supplies are much better sounding than some newer types. It all depends on the design. Many top notch DACs are using the same type power supply designs they have been using for the past 15 years or more. 

The biggest difference in DAC sound quality is if the DAC uses a DAC chip or a programed FPGA chip for the SDM and of coarse the analog output stage design as well as a quality power supply. Age has nothing to do with it other than electrolytic capacitors drying up and needing replacement.  

For example a 15 year old DAC that uses a DAC chip will not sound as good as a well designed 15 year old FPGA SDM programed DAC Like a ring DAC, A Ladder DAC, a DSD DAC ect....

Many vintage power supplies are much better sounding than newer type. It all depends on the design. Many top notch DACs are using the same type power supply designs they have been using for the past 20 years or more. 
 

@jk_richards

I am referring to the electronics that do the actual conversion of digital data to an analogue signal and not the power supply. 
 

The modified Directstream DAC I posted made in 2014 will sound much better than most modern DACs costing up to $15k 

If the big selling point of a new DAC is that it uses the latest and greatest DAC chip and does really high sample rates or DSD rates... that's a DAC that will be superseded quickly when the next chips launch in a few years.

Meanwhile a lot of DACs, both new and old, focus on the holistic approach for quality conversion (regardless of chip spec wars), well implemented digital filter, robust power supply, etc. Those are the DACs that stand the test of time.