McIntosh C52 to C53?

I wouldn’t spend money on the C53 just for the DA2 module.  You’d get better mileage out of spending that money on a separate DAC.  Keep the N10 and C52 and buy a DAC.  You could get an outstanding one for the price of a C53.

Another vote for separate DAC and leave everything else as is until you’re ready to step up to Aurender N150 or N200. I see DA2 upgrade in C53 as sheer convenience and not a day and night SQ upgrade. 

I had an Aurender A10 with the built in DAC and it was not as good as the built in DAC in my Mac C2700 ( DAC2 board) in my opinion anyway. The Aurender DAC was dry and rather boring sounding, the only thing I found it exceled at was it had a very low noise floor. The MAC DAC 2 board is really good for the money, but most DAC's above $2500 will out perform it. You can put a DAC2 board in your current C53 I believe. The HDMI ARC connection is great if you have a TV in the same room so that may be a factor. 

That said I got a Chord TT2 to try and it blew the DAC2 board away in all regards, I now have a Chord Dave i got used and its even better.

So a DAC is probably the best way to go IMO. 

As others have said, get a good dac. My C2500 has the DA1 dac and I prefer not to use it. It is based on the ESS chip which I am not fond of. I find it too forward sounding. Suppose you bought the C53 and a better dac comes In a newer Mac preamp. You would be constantly buying preamps with the latest and greatest.