Looking for recommendations on Tube AMPS to drive Monitor Audio Platinum Speakers

I have Monitor Audio Platinum 100 ii Bookshelf Speakers. I am Interested in anyone who has these speakers or heard them and can offer insight into which amplifiers may have driven them well. My preference is for Tubes and I have an Ultravalve (ST-70) that does not always seem to be up to the job. My prior Monitors were Sonus Faber and were easily driven by the AMP but these only some of the time not always. I will listen at higher volumes ¼ of the time.  Enjoying Rock (Classic), Jazz and Jazz fusion.  My Preamp is an Atma-Sphere UV-1.  I use Morrow Audio Cabling PH-6. Vinyl listening is preferred. Acoustic Signature/Ortofon-Quintet Black/OrtofonVertoSUP. For Digital I listen thru PSaudio Perfectwave Dac.

Mark