Gigabyte Z270M-D3H. Has PCI slots. Problem solved.
I wouldn't give up that Audigy 2. That was a good card. You won't beat it with a modern card.
If you do want a modern solution, I suggest an external unit (referred to as a USB DAC) which does not suffer from noise or interference like internal cards. Creative, Sennheiser, Oppo, AudioQuest, Arcam, and many others make them. You can get 5.1 and 7.1 units, though most are just stereo.
Remember that you can use multiple audio devices simultaneously in Win7 and later so you can have a stereo external DAC with no mic input and just use the mic input on your mobo or a USB mic.