Buy a $40,000 used DAC for $4,000 or a new one for the same amount?

“New DAC's are sooooo much better high resolution files hardly are necessary”

erik,  I beg to differ here. Either you haven’t heard a high resolution file or you simply find 16bit/44.1kHz files more than adequate. 

Depending on the original source master, the high resolution files 24bit/192kHz and above sounds better than their 16bit/44.1kHz counterparts. Not that 44.1kHz files sound bad, the high resolution files simply uncovers more subtle nuances, warmth, depth of field and air around instruments and musicians. Of course, all of these ‘audible’ subtleties are very much system dependent. 

I have 25 year old Wison Grans Slam Series 1 that I was offered 4k for (original cost over 50K). One twitter was shot and the smaller woofers had to be reconed. I decided to refurbish the speakers and the total cost was about $1500. The speakers sound like new and I have not heard better (though I am sure better speakers are out there). 
I wonder what 40K speakers he is referring to.

I see all of your posts are asking the same thing.  Just because a product retailed for $40K does not mean anything.  I have read where people say something is built like a tank.  All this means nothing until you understand design and what makes something sound good.  A heavy chassis does not mean built like a tank.

It comes down to the design and parts used.

the high resolution files simply uncovers more subtle nuances, warmth, depth of field and air around instruments and musicians.

This statement is simply not true at all.  Most high rez files do not have warmth compared to properly designed NOS DAC designs.  They may have more detail but in my experience give up the musical sound quality that NOS has.  But having a DHT DAC, I don't give up anything.

Happy Listening.

I would  rather have a 10 year old 40K DAC for 4K than a brand new 4K DAC.  It would be a leap of faith but my guess is the 40K unit even at 10 years old will still be better.  I recently compared in my home a 35K DAC setup with a 5K DAC setup and it's not even close, sorry to say but you are really missing a lot with the lower cost setup.  I didn't want it to be true but it's just magic with really nice gear like that. Guys can kid themselves all they want that there isn't a big difference but there is to my ear.  Maybe some people jump in a porsche and think it's not better than a toyota so those kind of products aren't made for those types.  

I’d take a T+A DAC8 DSD over the old DAC no question.  The majority of that $40k you paid for back then was R&D that’s been surpassed.