Tiny speakers sound tiny when they produce significant levels of distortion, and don't have deep bass to help "cover" for this. In this sense physically larger speakers, which in fact nearly always means a structure required for producing deep bass, typically do a better job of fooling you into thinking you have good sound because the bass rumble is doing a fair job of compensating for the upper ranges not quite working properly. How many people here put quite some effort into giving a downward tilt to their system's frequency reponse, and are quite pleased with the result? How many people can't stand Wilson speakers because the treble projection on these takes no prisoners? If all else fails push that which is not quite right more into the background ...'tiny' speakers sound 'tiny' in the context of SOTA.
Agreed, all things being equal, a setup with performance reaching into the bass will be superior than one without, but from where I stand nearly all of the musical action occurs beyond the bass region, so I want to be sure that that is working correctly first. Tim's solution is probably ideal, a good 2 way, then subwoofers to add the grunt as required. The trouble with bass is that you need big, heavy lumps of metal and cabinetry to do things properly and that equals money.
I have listened to "tiny" speakers working at deafening levels and have enjoyed the energy of the pure, clean music washing over me; when operating like this the last thing they sound like is tiny. I have also experienced monstrous, exorbitantly priced behemoths hooked up to similarly priced componentry at very moderate levels, and figuratively, run screaming from the room. So, again, the size and price of the gear has almost nothing to do with the quality of the listening experience ...
Frank