Power Categories

20W Between 20W and 30W, music is essentially lifeless, but it can hold a good tune. Essentially, products like Rotel are essentially headphone amplifiers, and a bridge to hi fi.

60W is essentially all you need, should the amplifier be properly made.
100W is typical. Music is full and poppy.
150W is where the interest starts to happen. You have a feeling of more power.
200W is where you begin to notice bass and drums having some degree of reality.
300W is where you begin to get excited. You have some proper feeling of power and authority to reproduce music.
600W is where you start to notice "fireworks" - you might believe that there is a sub-woofer present, and sound staging may be impressive in height and width, if not depth of field.
1000W is where you start to have a feeling of PA power - of the the control of a night club or a stage concert. It's not that, but you can start to produce music at this power.
1500W or more is where we start to get interested in which speaker just might handle the juice.

Note that we are talking essentially 8 ohm power ratings, for speakers typically rated at 4 ohms, nominal.

Most hi-fi speakers operate between 3 and 8 ohms.

If an amplifier is properly designed it essentially doubles its power into 4 ohms, and possibly, in superior circumstances, into 2, and rarely into 1, or 0.5.