Can i safely connect 100W speaker to a 50W amplifier and 50W speaker to 100W amplifier?

50 watt amp to 100 watt speaker is okay 100 watt amp to 50 watt speaker is not a good idea. You could blow the speaker.

more speakers are damaged by using too little power and cranking them i have 3 150 watt mtx subs powered by 900 watt alpine turned up no problem had 2 10 inch kickers combined handled 600 max same amp ok but under powering them causes more heat can fuze voice coil also have 800 watt amp powering 4 little speakers for dash and 2 4by 10s just turned down low and mid on amp

The speakers must be always more powerful then amp. Fo 50W amp u should connect about 150W speakers. U can also connect speakers with 50W but in serial connection that will make it as one speaker of 100W if u can understand that. U can connect speakers with more ohms. If your amp require 8omhs u can still connect like 12ohms speaker but u will lose a little power but it is safe.

In fact I would reccomend a 100W amplifier connected to 50W speakers - a high powered amp will provide more current and greater control - useful attributes for detailed and controlled bass. However, don't crank the amp up all the way or you will risk blowing the speakers. Same actually goes for a 50W amp - if overdriven it will produce nasty distorsion which could also blow your speakers.

In addition to knowing the numbers (specs), I'd recommend some 'pre-shopping' research (read audio reviews etc. and check out how they 'mix & match' components.) Why? Knowledge can save you (a lot of ) money. The alternative would be to ask the salesman... How much power? I shall not debate on this (the debate still goes on!) Alternatives to amp and speaker separates: Go powered. I would recommend powered speakers. Powered speakers have built-in amplifiers. If you want to go cheap, go for computer speakers. CNet has helpful reviews. ... Or go for 'pro audio' (studio gear etc.) I personally use powered studio monitors. Of course, 'pro audio' has its own specifications and requirements, which vary from that of 'home audio'. Here's my additional 2 cents of input: It takes a lot of power to reproduce very low frequencies. This in itself can be an interesting topic. Also…having the world's best speakers doesn't guarantee you the best sound. A discerning customer once informed me that a pair of B & W Nautilus floorstanders in a local record shop could have sounded 'ten times better'! And why not? The present amps (expensive monoblocks, mind you!) were not suitable for the Nautilus (insufficient power; 'wrong sound’). ...Do let your ears be your guides too. Happy shopping.

Speaker impedance should be matched to amplifier output impedance for optimum audio performance