stereo wattage output - speaker wattage

Remember head unit ratings are generally at max (or near max) volume. Where as speaker rms ratings are what they can cope with constantly. If you're running 60 watt rms speakers with a 50 watt head unit, it's a pretty good match. It means the speakers can cope with more power than your head unit can put out. In theory they may be slightly quieter than 50 watt speakers, but in a car with all the other noise from road etc it's not really going to be noticeable, and it's safer for the speakers in the long run if they can cope with slightly more power than the unit puts out. You only run into major issues if there is a larger difference between their ratings. Eg, a 30 watt speaker on a 100 watt source has more of a chance of blowing the speaker, or making it distort. On the flip side, a 30 watt source with a 100 watt speaker will be quieter,and you'll tend to turn the volume up higher, making the head unit work harder.

There are a heap of other variables that can affect the sound like the efficiency of the speaker, but as I said first, the match you've got should be fine.

 

A 4 x 50w headunit will put out 4 x 20wrms at best.

 

no its not. the speaker will clip and sound like ****.

60 watt rms speakers need a 60 watt rms source. not a 50 watt peak source.

either get an amp or get different speakers

 

It will do no such thing. The SIGNAL will be clipped if you push the H/U's amp too far. But I could run a 500wrms speaker from a 1wrms source easily.

It seems a waste to upgrade the speakers without upgrading the H/U and an amp, and quite often it will be quieter because the factory paper speakers have a fairly high sensitivity rating.

 

My factory speakers were quieter than the Alpine 6.5 inch speakers I swapped over for. It also introduced a substantial amount of mid bass and improved to a lesser degree the bass.