If you can use 500w/ch and speakers are not a horrible load to drive those are an affordable option. I would not use them with a tube preamp in that they use native icepower modules with only 10kohm input impedance as I recall.
I have ref1000m model. These have custom input and power sections to enhance the basic icepower module. These cost more but work better with tube pre-amps and harder loads to drive.
I have ref1000m model. These have custom input and power sections to enhance the basic icepower module. These cost more but work better with tube pre-amps and harder loads to drive.