DAC's from the past, are any of them really worth much today?

I must add that for sure you are right ... Any high end system will operate from a file bank in a dac not from the computer...Once this is said ...

My point is that at low cost an audiophile experience is possible even from a USB connection from the computer ...😁

The electrical noise floor level of the house for example can be also a factor more impactful than the computer noise... The speakers resonance can also be way more impactful ... The room acoustic can be way way more negative too ... Each case differ ...many factors are at play ...

My USB computer connection is not ideal but the acoustic experience is so good already i cannot even think of upgrading it ...

I can’t think of why anyone interested in high end audio would want to have anything to do with USB. It was brought on board because of the PC. No high end system should have a computer in the loop… hence no use for it.

Funny your comment @ghdprentice all the high end streamers/ servers from Innuos, Taiko, and the like use USB, using usb is not for pc any more.  Take a look around even Grimm has USB capabilities. 
 

I can’t think of why anyone interested in high end audio would want to have anything to do with USB. It was brought on board because of the PC. No high end system should have a computer in the loop… hence no use for it.

@jacobsdad2000  The DAC I am demo'ing has no usb connection, because it is too old! This will prove to be a considerable detriment to usage as it cannot really connect to today's better streamers, along the lines of what you post. It does have Co-ax, which I am hearing differing things about, some folks tell me that Co-ax sounds worse than today's USB, others better?? Nonetheless, since the better streamers use usb only, it is not a connection option. 

.... some of the lowest price DAC’s are to be had from yesteryear.

WRONG

And many new cheapies out perform most of the 20th century designs.

Only for enjoying music.

@daveyf Hey it's what works for you. Digital wise I have used them all and AES/ Balanced, Optical, USB and SPDI/F Coax, key is use a good 75 ohm cable.  Signal makes some fine digital cable as do DH Labs. Better yet buy used. Look here and on USAM.