Your speakers' sensitivity rating means that a mere 1 watt of input will produce 87 dB when measured from 1 meter away under test conditions (in an anechoic space). 87 dB is already pretty loud, but every doubling of distance from the loudspeaker under controlled test conditions results in a 6 dB drop in the speaker output. Let's say you sit 4 meters away, which means you've doubled the 1m distance twice with a theoretical drop-off of 12 dB. You're still getting 75 dB from a single watt, even with those "inefficient" speakers.
Now, for some people, with some tastes in music and volume preferences, in some rooms, even 75 dB might be loud enough ... IF we assume we don't need extra headroom for transient increases. But we cannot assume that. You might need (or want) an extra 15-20 dB headroom to handle those musical peaks.
Every 3dB increase in speaker output requires double the wattage. Those transient peaks (or just cranking up the volume a bit) might call for 6, 7, or 8 doublings. So if your speakers are nominally 8 ohms, then you might want an amp with a little more juice. But it really depends on many factors. You're already ahead of the game if you like what you hear and don't notice any clipping. More watts, per se, probably won't widen/deepen the soundstage. For that, I've found that speaker placement has the biggest impact. The trade-off is that, if you bring them away from the walls (on stands) to deepen/widen the soundstage, then the bass impact will drop off. To compensate, you might want to try a small powered subwoofer. Meanwhile, if you are sitting closer to the loudspeakers, that should let you get by with a little less volume.
Now, for some people, with some tastes in music and volume preferences, in some rooms, even 75 dB might be loud enough ... IF we assume we don't need extra headroom for transient increases. But we cannot assume that. You might need (or want) an extra 15-20 dB headroom to handle those musical peaks.
Every 3dB increase in speaker output requires double the wattage. Those transient peaks (or just cranking up the volume a bit) might call for 6, 7, or 8 doublings. So if your speakers are nominally 8 ohms, then you might want an amp with a little more juice. But it really depends on many factors. You're already ahead of the game if you like what you hear and don't notice any clipping. More watts, per se, probably won't widen/deepen the soundstage. For that, I've found that speaker placement has the biggest impact. The trade-off is that, if you bring them away from the walls (on stands) to deepen/widen the soundstage, then the bass impact will drop off. To compensate, you might want to try a small powered subwoofer. Meanwhile, if you are sitting closer to the loudspeakers, that should let you get by with a little less volume.