Best tube mono blocks under $15,000?

As we speak ther are a pair of Mc 2301's just under your budget (14995). I would check em out, just popped up in the classifieds.

MC 2301's seem like the obvious choice.

They seem a little over the top anybody ever ABed them with Mc275?

Try BAT VK-150SE or BAT VK-55SE. I'm not sure of the price.

Atma-sphere MA-1's should give you everything you need as well as heat your home. As with all amps speaker match is very important.

Power rating: 150 watts/channel into 8 ohms/145 watts into 4 ohms
Power bandwidth: 2 Hz - 75 kHz within .5 dB
Frequency Response: (1 watt): 1 Hz - 200 kHz within .5 dB (-3dB @ 1 Mhz)
Phase Shift: less than 1 degree @ 20 kHz
Power supply storage: 600 Joules/chassis
Output section rise time: 600V/micro-second

Power consumption: 500 watts/chassis
Tube compliment: 14 6AS7s and 4 6SN7s per channel
Input impedance: 100k/ohms single-ended; 200k balanced
Output impedance; 1 ohm
Signal-to-noise ratio -95 dB