The mode buttons are explained in the manual. They are basically there for different types of cans and microphones.
The stock opamps actually sound reasonable on this card but the card can sound so much better with some opamap upgrades. They are meant to be changed out so Auzentech used generic opamp to keep the price down.
I know the card supports opamp upgrades. That's why I asked about it! I sort of explained what I had previously and liked and what I use for hearing devices. Again, I was hoping someone with more knowledge than I could add some witty or intelligent suggestions.