RMS is the worst term ever devised, its a stupid marketing gimmick so hifi manufacturers can put stickers on their units says "1200 watts RMS" http://www.webopedia.com/TERM/R/RMS.html I don't often see speakers quantified by RMS values, its normally reserved for amps etc. Speakers normally just have their power handling printed on them, which isnt RMS. What is the impedance or the speakers 8ohm or 4ohm? at the moment I have a 40w per channel amp running speakers that are capiable of 120watts, and that is just fine. Conversely my bass amp is 500w but my cab is only 350w, in applications like this you need to headroom to stop distortion etc. what is the amp and what are the speakers?
It's the impedance you want to look out for. This is measured in ohms. What are the ohms of the speakers?
It is an old Kenwood AX-33 I have lying around and i hope to match it to http://www.maplin.co.uk/100w-8-inch-loudspeaker-47380 these speakers as a small system for my bedroom
RMS is usually to give a fair idea of how load an amp/speaker combo will actually be, as the PMPO can be very misleading. I once had 2.1 computer speakers that advertised itself as 500w PMPO but it clearly wasn't or it would have shaken everything in the house. Turns out the sub was actually 35W and the satellites were 5w each. I then upgraded to a 60W Cambridge amp with 100W Celestion speakers but if I turned the amp above halfway it would blow the tweeters. My guitar amp on the other hand was a 100W Marshall head with a 4x12 cab that could handle 300W, it's RMS was around 180W which was a much more accurate representation of how loud it could be as it was much much more efficient than the "500W" computer speakers (and could rattle everything in an old farmhouse with very thick walls)
I still don't really think RMS is a good representation of anything. If you want to measure how loud something is, get a SPL reading, tis the true representation of "loudness". I used to have a 5w per channel (2 channels) valve amp, driving my old ditton 33's and it was very loud indeed - and 33's are only 80w max speakers, the RMS of that system would be tiny, and not at all a true representation of how loud it is.
