If you're looking at the Super mini or Super 7, then a better comparison would be the X1, X3 or X5, since all of them have self-powered bass sections. IME, if you're looking at using a 2a3 (3 or 4 watts max), then these types of bass-powered speakers are better choices than the passive full range speakers.
If you're really focused on the M3 or M5, you're better off getting an amp capable of more watts, like the Dennis Had Inspire Single Ended Pentode (up to 14 watts w/ a KT150), or if you can find a used Almarro A318B, it will give you 20 watts pure SET. Or even a good quality push pull amp, like the Don Sachs Kootenay. As you can tell, I'm a fan of amps using 6SN7s in the driver position