In that one cannot have all three of bass, efficiency and small size in a speaker its a useful exercise to rate a hifi speaker in each of these categories.
Being conservative on a scale of 1-10 for my Triangle Titus XS:
bass - 6
efficiency - 7
small size - 9
I also have Realistic Minimus 7s that I think could work well within their limits off a SET amp
bass - 4
efficiency - 5
small size - 10
Dynaudio Contour 1.3 mkII
bass - 7
efficiency - 4
small size - 8
OHM 100 Series 3
bass - 8
efficiency - 6
small size - 6
Adding good powered sub set up well to the mix eliminates the limitations in most all cases.
Being conservative on a scale of 1-10 for my Triangle Titus XS:
bass - 6
efficiency - 7
small size - 9
I also have Realistic Minimus 7s that I think could work well within their limits off a SET amp
bass - 4
efficiency - 5
small size - 10
Dynaudio Contour 1.3 mkII
bass - 7
efficiency - 4
small size - 8
OHM 100 Series 3
bass - 8
efficiency - 6
small size - 6
Adding good powered sub set up well to the mix eliminates the limitations in most all cases.

