Upgrade DAC or Buy New

5 Y/O dac technology is ancient

Check out PS Audio new DAC (MSRP- $995). Cullen and Underwood modifies them if you want it to take it to another level

"5 Y/O dac technology is ancient"

Yeah, but I know of some manufacturers that are still using the 'ancient' Burr Brown 1704 DAC in their new equipment. It is used in the Muse (4 of them in dual differential balanced mode). Steve Nugent at Empirical Audio uses them in his $6K Spoiler DAC.

I have the Accustic Arts Tube DAC and absolutely was stunned when I first heard it. You can get their now discontinued Mk. 3 version for around $2-2.5K. I am pretty sure that will be a big improvement over the 2003 DAC.

There is nothing wrong with an older dac. Zanden uses a dac chip from the late 80's early 90's in their $10k+ signature dac. Tubes are not new technology. If you like what you have and feel you need more drive to your amp than maybe a good used preamp might help. It would be a shame to upgrade your dac and then miss the magic you are now enjoying. I went down that road years ago and it took me years to get back to where I was.

I don't know about the particular units you are talking about, but it is wrong to assume that more recently designed DACs are superior to older models. All manufacturers are dependent on the chips that are available on the market. New generation of chips are often inferior in sound quality to older chips. The new chips serve more functions than the older chips or better serve other priorities. For example, new chips are optimized for much lower power consumption so that they can be used in portable devices; who really cares about sound quality? Some manufacturers have actually stocked up on vintage chips to use in their premium models (e.g., Naim).