What about improved quality caps in the crc circuit you speak of? Especially since the 2nd c is downstream of the fets. I was actually thinking of putting polyfilm caps in this location, but that may be foolish overkill. Replacing the coupling caps is absolutely necessary IMO. Difference is not subtle.
Swapping out the 220 R's looks straight forward, but where do you sneak in the bypass caps?
I have misplaced my Dac-50 circuit diagram (95% the same as DAC-60.) But I am modifying another for my brother this weekend. I'll get everyone
a list and photo's. This mod is a level above the Sonicrafts to my ears. There is another person on this forum that should get credit
as it was his original idea (along with Jim Hagerman.)
Here are the changes:

The trick is the cathode by-pass caps (c1) almost doubles the gain which alows you to lower the I/V resistor. With pasive I/V lower resistance
sounds a lot better. The 220 ohm is way too much. The circuit above goes another step better in replacing the filter entirely with a smoother sound and higher quality inductors. You also want to use the thick film resistors, I can give my digikey part #'s if anyone is interested.