SACD Player Mods vs. Outboard D/A converter?

In terms of absolute bang for the buck, I'd go with some mods from someone like Dan Wright. If you're willing to spend $2000 or more for the DAC, you'll probably get better performance from the outboard unit. I previously faced a similar situation when I was using a Chord DAC 64 with a Sony SCD-333ES and an XA-777ES.

Geez me too, somewhat...

I just took delivery of a used 555ES that I can't play until my new amp comes in a few weeks and I'm glad I didn't release my CI Dac yet anticipating that the stock 555ES redbook may be something like my original 333ES was (which I had "Kerned").

I can say that after Richard modded my 333ES the redbook jumped substantially forward in musicality (hackneyed term I know). The SACD section was better but not like the redbook was. Based on that experience I am prepared to leave my 555ES stock for SACD and use it for a transport for my DAC (which I dearly love at its pricepoint).

Maintains the Sony ES warranty, gives me what I am hoping for is pretty good SACD (based on stock 333ES sacd in my past) and gives me a good bang for the buck - not nearly the best mind you but enough for now (or until I talk myself into sending it back to Oregon...)

Get a Chord DAC 64 and any transport jumps levels in musical presentation. I have one and use an Electrocompaniet, a Pioneer 300 disc changer, and a Sony 333 changer as transports. All sound great through it with no mods.