Since you'll be driving speakers at low to moderate volumes, I'd suggest you get either the M3ti's or M22ti's, preferably the M22ti's because their sensitivity is 2 dB greater which, with your tiny amplifier, is significant. Either model has usable bass to 40 Hz (nothing below that). You can check out wall-mounting brackets at omnimount.com, vogelsusa.com or btech-usa.com.
By the way, about "requiring efficient speakers". No small ported or sealed hi-fi speakers are efficient. Only horn-loaded Klipschs, Tannoys and the like have high sensitivity but the trade-off is inaccurate colored sound and aggressive treble. However, as long as you are not trying for concert-hall levels, you should be ok, and tube gear tends to gradually "clip" with more tolerable distortion.
Axiom Resident Expert