Which Tube amp is most refined, Stereo 40 MKIV Signature or Raven Audio Blackhawk MK3.1?

I just posted my review of the Raven Audio Osprey Integrated Amp (same upgraded components/sound as the Black Hawk). While auditioning amps, I did get to hear both the Osprey and Black Hawk. They are AMAZING. Here is my full review:

Raven Audio Osprey and Corvus Reference Monitors Review

Unfortunately I've never had the pleasure of hearing the MKIV Signature. However , I do own the Raven Integrated amp you mentioned. Several years now I've enjoyed the stunning realism of the Raven. Musical, organic, pulpable, and by all means 'refined'. A beautiful unit which, as you say, offers the by pass for sub out leaving the amp free to maximize power to less demanding tasks. After I used the "pass" with the SVS SB2000 sub I never looked back. Everything opened up even further and my Lascalas  produce crisp clear refined musical magic. Thats my input for what its worth without auditioning the MKIV.