Preliminary report...(couldn't wait for the capacitors to come)
Wow, I took out the (most certainly knockoff) NE5532a's that came with the amp, swapped them out for the
LM4562NA --- Sound phenominal
OPA1612AIDR --- Same as above
ADA4627 --- Wouldn't work, realllly low and heavily distorted audio, gotta look into why
NE5532AP --- Slightly lower noise than the stock ones, none of the distortion.
My first impression, when I plugged in the amp for the first time, was "There's no way anyone can think this POS sounds good!"...to the point where I questioned if people on here even knew what good sound was. I guess my opamps were just that bad, the distortion was heavy. I mean I couldn't listen to it for more than 30 seconds without just shaking my head and saying "nope, no way, there's no way in hell I can accept this thing".
After the opamp swap, it sounds amazing. In my case it made THAT big of a difference. Sade's Jezebel no longer had fuzzy vocals trying to compete with the saxophone. It sounds as good as it does in my car....(which says a LOT btw).
I'll have the measurements as requested in a prior post once I get the caps in and open it up again. I'll keep you guys posted.