Another vote here for the M33.Had mine for several months now and it still blows me away, playing out to a pair of GoldenEar Triton Ones.
It's recently (finally!) been Roon certified and that has just made the icing on the cake for this slick and sleek all-in-one. The BlueOS is a matter of personal taste (I quite liked it - no big issues) but other's mileage may vary there - but with Roon you can by-pass that anyway..it'll love your Roon Nucleus...especially if used with ethernet.