I believe the opposite. You get more with a $1000 new DAC than am older one. I have 2 DACs in that price range.
- Topping D90SE very neutral and do not expect any warmth from it ($900)
- Gustard X26 Pro it has more variation in sound with the filters. It is not as detailed as the Topping D90SE. It goes on sale for $1250
I cannot think of any older DAC that I would take in place of a high quality (cheap) new DAC
If your system is capable, you will hear differences with DACs, but it is not going to be a huge difference since most DACs these days are awesome. My price limit for new DACs was 2K for the last little while. However, I went 'crazy' and spent $3K for the Musetec 005 DAC and it is definitely the best one I have ever had. More bass, denser sound, not bright on top., with detail.
The other 2 DACs I mentioned also have most of those attributes but the degree of each is not at the level as the 005.