bobruz's post in A good power amp for Helix to drive guitar cabinets was marked as the answer
Check out the Koch ATR-4502, single space, tube hybrid stereo power amp. (45W stereo or 90W momo)
I use one with a Wizard cab loaded with a Celestion Vintage 10 and a Jensen Falcon 12.
Helix sounds quite nice. Plenty of dynamics and volume when needed.