Ext. Dac. - is it worth it?

If we believe german magazine "Audo" then the answer is NO.
This magazine tests many different audio gear and publishes the results in points.
The test results are showing that dacs are usually much higher prized. For example I show some test results from "Audio".
The highest points for digital source were given to DCS Verdi/Purcell/Elgar plus = 140SACD/125CD
Burmester 970 = 115
Mark Levinson 360S = 110
MBL 1611 D = 120
MBL 1511 = 100
Same 100 points gives Marantz CD17MKII for the third of the prize of MBL.
CDP list
Burmester 001 = 115+
Accuphase DP-67 = 125
Accuphase DP-85 = 135SACD/125CD
Wadia 861 = 125+
Linn CD 12 = 115
Krell KPS5s = 120+
Marantz SA-1 130SACD/115CD
Marantz SA-11 S1 = 125CACD/115CD
Meridian G08 = 115
Of course this is not absolute truth because sources with same points may be sonically wery different, but these tests are wery useful for showing approximately the performance/ prize ratio. I hope this helps.

if you have a wadia 861 and to try a "new" sonic signature then yes it is worth it..

add a reimyo, audio aero, or lecteur dac (totally different signature than what you have now) you have a world class transport..

or if you like the wadia sonic signature and wanted more the
send it to steve huntly at GNSC to push the sonics of your wadia to the limit..

I agree 110% with Plato.