rega osiris vs simaudio600i or?

I need to disagree with you Meiwan. In my opinion, the Osiris can be considered even " cheaper" compared to the top integrated amplifiers in the market ( I mean Dartzeel, Gryphon, ASR, Vitus, Boulder - the ones I have listened ) . In my opinion, it is in a different league compared to Sim Audio.
My last integrated amplifier was a Gryphon Callisto, 2200, with An. Upgraded pre amplifier circuit similar to Gryphon Diablo and I think the Osiris even better.
Each of the mentioned top integrated amplifier has its own qualities and can even better match your taste than Osiris....but without doubt the Osiris has the same overall refined sound.

hba what kind of speakers are you running with the osiris

Look at Neodio NR600 signature. If there is a better sounding integrated I have not heard it. 100 watts ss, French made. BTW I own the Rega Isis cdp, the best player in my system under $10,000. Let me know if you want anymore infor on the Neodio.

But what are your thoughts on the rega

I have not heard the Osiris but since it is the cousin of the Isis I am sure it would be exceptionally good.