I will be the contrarian here. An AHI of 6/hr or 9/hr is not even classified as sleep apnea in certain countries. Since your O2 sat were good, you don't have this problem. I think a xPAP machine is too much of a hassle for such a minor case.
You may want to get a lab sleep study done if you want to be really sure but a home study with o2 sats provides a good picture already. Also, a sleep study in a lab can tell you if you have UARS. That may cause daytime tiredness as well without an uptick in AHI. A xPAP machine will take care of that as well.
You may hold off on spending $$$ for a machine and mask, for now.
My 2 cents. YMMV.
Started APAP 4-20, Closed range to 7.5-14, then straight 8.0 w/ Aflex 3
RDI always below 1. But sleep much much better at straight pressure.
Started on F10, Tried Quattro Air successfully. Finally settled on P10.