If it helps, I have a pair of JBL LSR32s (93db into 4 ohms, -20db at 20 hz) and AVA's amps have never blinked. I made them go loud enough to fill a "lively" 5000ish sq ft room (no carpets). Now these were bigger amps, hybrids, and things were done (double-die upgrade), but they were not required for normal operation, just surprising upticks on SQ instead.
I also matched them up to good effect with the 30ish watts of the UltraValve.
So I just assume that fewer watts do not change the basic attitude that low impedance shall not be an obstacle over at AVA. Nonetheless, (a) 30-day no hassle return, (b) if you do encounter a reasonable limitation to this amp like the one you're describing, you will probably be "the first house on that block".
You might consider paying a little extra and getting one with a volume knob, 'cause you never know...