I would get the Monitor 40 speakers for the front and use the Rti28s to replace the Insignia speakers. The Monitor 40 speakers will do a much better job in that rather large room. Note that the Monitor 40s are rated to operate up to 250 watts of power and the Rti28 are only rated up to 125 watts.
The larger speakers can put out greater power with lower distortion; two 5" drivers in a larger enclosure move more air much more efficiently than one, in general.
Also, the Rti28 speakers are really only fully effective down to about 70 Hz; Front speakers for a room like you have really should be able to go down to around 50 Hz for proper multi-channel mid-bass sound, and the Monitor 40 speakers will do that. When you say that bass response is not an issue you are 100% wrong.
Remember that a subwoofer is MONAURAL, and is no substitute for having front speakers that go fairly low and using them fully. The subwoofer is there ONLY to produce the lowest frequencies that your front speakers CAN NOT put out. Why have 5 speakers and then allow a significant part of the sound to be monaural when it should be stereo? How much sense does that make?
I think that you will find that the Monitor 40s will be a great improvement, and that the bass they put out will be make the sound much better in the room. Having the larger front speakers to produce that critical mid-bass from 50 to 70 Hz will be a huge improvement in the way your system sounds IMO. I have seen this kind of change totally transform a system over and over. Front speakers that are too small are a big problem that too often goes unrecognized, and it is certainly the problem in your case.
Originally Posted by Jukebox305
I am wondering if having multiple drivers (MDM) on a bookshelf speaker is going to improve the overall sound of my room or possibly make it worse. My system in a medium size triangular room (15x20x25) and the closest speaker is about 5 feet from the listening position. I have a Polk CS1 center, rti 28 L/R bookshelves, and two pairs of terrible insignia bookshelves for the surrounds.
I don't know if I should go for two Polk monitor 30s for the front and some Polk OWM3s for the surrounds or monitor 40s for the front and OWM5 for the back (or possibly another combo? 40s/OWM3?). My main goal is to play music and have it sound great throughout the entire room when I have people over for parties. Also I have a subwoofer so bass response is not an issue.