I suggest an Odyssey Khartago stereo power amplifier. They are not too expensive, but definitely high end. The PASS Labs x150.5 is also great, although much more expensive. The amp must drive 4 ohms loads well(high current).
Mate that with a good tube preamp (too many to mention) and you are good to go. You could also go with a used "classic"
preamp. I use an Audio Research SP-14 and alternate with a Pass Labs X-1 on my Magnepan 3.6's.
Contrary to popular opinion you do not need huge amounts of power. 100 to 150 wpc will do in most average sized rooms for sane volumes.
As "Philjolet" said a Quad 909 should work.
What is your price range? The 1.7 is not limited to inexpensive equipment. You can spend big bucks, and the sound will improve that much more.