Maticulus.

(great info Jim.)

my reply...to add to jim's info.

1..lots of us here use rb. ive lost count how many songs.
so its a question of setting things up correctly in windows and rb.
2..you said ' I've been using BIAB for about 8 yrs now. Each year I plugged a microphone into the mic jack of my PC and played back whatever I put into it...'
my answer is in this case you would have had latency if useing on board pc sound.
the preferred way is mic>>usb interface or mixer (in your case harbinger)>>pc running rb or whatever multitrack daw.
this is the norm.
3..as youve been running bb fine for 8 years please post pics of biab audio and midi driver settings.

om

my songs....mixed for good earbuds...(fyi..my vocs on all songs..)
https://soundcloud.com/alfsongs
(90 songs created useing bb/rb)
(lots of tips of mine in pg tips forum.)