Why not check out the VTV Purifi Amplifier with custom input buffer. Select the Opamp or Tube input of your choice. Check out my Youtube channel DIY HiFi Life for details.
https://youtube.com/playlist?list=PL3kctOR1C3QqHG0IjdHi9_mQlY5XGmuJl
https://youtube.com/playlist?list=PL3kctOR1C3QqHG0IjdHi9_mQlY5XGmuJl