It is most defiantly not plug and play...
Here are my samples of the PCM1772 there are 3 of them in the black carrier next to the Canadian Dime for size reference.
They are 16 Pin TSSOP which is 0.3mm pins with 0.65mm spacing, so you'll need SMD soldering skills and some good eyes.
Here is the part of the board where you change the chip highlighted in green, this is on the screen side of the board so the board will have to be removed from the case.
Electrostatic handling precautions need to be observed as always.
The parts highlighted in red are designed for the HP Out of the 1770, the Data sheet of the 1772 recommends a LPF on the output of the chip.
The PCM177X demo board has a OPA2134A 54 kHz / 108 kHz second-order post filter, but you should be able to get away with a passive LPF, only it will give no where near as much output level as the OPA2134a does, and I don't think there is enough room for an opamp inside the case.
Since this might just be an exercise in futility...
I have sampled some PCM1770's as well to put things back to rights if need be. I am going to borrow an oscilloscope from a friend before I do this to measure output levels and look for any strange oscillation's, I wouldn't do the chip switch without one.
Also not knowing how good the traces are on the board, I'll just cut the 1770 away from it's pins and then clean up the old pins to minimize lifting any traces.
And that jdog is as far as I am at right now.
I will post more details and pictures when I do the swap.