bigger speakers = bigger better sound.
Uh..........not quite that simple.
Better frequency responce, drivers, enclosure, voice coils, internal wiring, external wiring, resonance tuning, standing wave elimination, lower total harmonic distortion, and on and on = better sound.
I've heard some mammoth speakers that sounded like crap. When compared to my B&W CDM 1NT's rolled of at 80 Hz to my Hsu Sub......well there really is no comparison.
Also a VERY good point being made here. Your final sound is only as good as the weakest link. The Droid's DAC (Digital Audio Converter) circuit is certainly NOT going to be anywhere near audiophile quality. A reasonable set of Sennheiser buds (about $20 ~ $25) reveal it's shortcomings when compared to an iPod Nano. You can hear the difference.
To tell someone here to invest in $100 to $300 earphones for their Droid is not doing them a favor. If on the other hand they want to listen in a controlled environment to a $5000 CD Transport with a $5000 ouboard standalone DAC those $300 earbuds would be a reasonable choice. But who in their right mind would be listening to earbuds with the good equipment? They'd either be using great speakers, or if they HAD to keep the noise down some Grado's or equivalent NICE full-size headphones.