Lampizator makes awesome DACs. I have a few customers running them and they love how musical they are. The stock tubes stink so assume you are going to need to replace those to get the most out of it. This is a bit below what I would define as "cost no object".
Regarding Roon, it has two parts. Roon Server and Roon Player. If a DAC is "Roon Ready" it is equipped with Roon Player software and serves as a renderer. It is always best to have those two things happen on separate devices. This is the approach taken by Antipodes with its servers and players though the player is unnecessary if you have a good Roon ready DAC. Off hand, I can't think of a tube DAC that is Roon ready.
To go beyond Lampizator, check out Jadis. The JS1 MkV is insanely good and is based around the AKM 4197 chip which is used in many of the worlds best DACs. Gorgeous in terms of aesthetics, and it sounds better than it looks.
Another alternative would be the Ypsillon NOS DAC. This is one of the most natural sounding DACs in the world and uses a very interesting approach.
Either of these is going to give you insanely good sound and naturally would be best paired with something like an Antipodes K50. PM me if you are interested in either as an alternative to Lampizator.