Hi,
Last version will come with DIP8 socket so you can update yourself the OP amps.
I am really familiar with OPA1656 but it was the first time I heard the MC33272 when I got the DrMordor module....
I really wonder how Drmordor module will perform with OPA1656 ) But certainly very well ! I do love those OP amps and I am using it for months on my TPA3251.
To compare : OPA1656 bring the Bursons V5I to their knees as well and keep in mind : Burson V5I = $70 vs $10 for OPA1656
OPA1656 is a ultra low noise fet operational amplifier and delivers a low distortion of 0.000035% (–129 dB) at 20 kHz
If you love the OPA1612 you will love the OPA1656 too. It is a very accurate OP amps with a linear restitution It is much less colorful than an OPA627 for example and it lets out all the micro details when listening
People were very skeptical about the impressions I shared on the OPA1656 and now many people use it even in this project :
https://www.diyaudio.com/forums/class-d/362341-aiyima-tpa3251-modification-build-thread.html