As I said, I have a small theatre with a 10 foot distance from the primary listening/viewing position to the front wall. And that's a good thing for these speakers because they will definitely reach their output limits in a larger room.
I'll just cut right to the chace and say that Revel's specs are spot on. They say you can pump 125-150 Watts into them and that seems right about perfect. No trouble hitting 85dB average levels at the seat and cranking them to hit 105dB peaks (which would call for around 100Watts at this seating distance and the stated efficiency of the speakers) basically had the speakers tapping out with the high frequencies getting very shrill and the high end of the midrange starting to sound really "crunchy" and brittle. In other words, they're about what you'd expect just by looking at them. Four 3 inch drivers and a 1 inch tweeter in a very small, light-weight package just isn't meant for a large room! But in my small room, from a little under 10 feet away, they can just barely hit reference volume, and I honestly wouldn't want to push them an inch further!
The other obvious thing - and again, Revel's specs are spot on - is that there is no bass to speak of with these speakers and the recommended 110Hz cross-over is exactly right. That's definitely on the high side, and makes it so that I'd definitely want a subwoofer at the front of the room so as to mitigate localization of the bass as being separate from the speakers. With a good sub that can play flat up to 200Hz though, the blend works perfectly with the 110Hz cross-over. I'd say a mid-bass module placed up front would work very well for anyone who needs to place their low bass subwoofer elsewhere in the room.
So there are definitely some limitations with these speakers, but I consider those limitations fair. Not just because of the price point and physical size, but also because Revel plainly states the specs and, so far as I can tell, those specs are accurate. They're not trying to claim deep bass extension or massive output capabilities, so you're getting what Revel claims - nothing more, but also nothing less. Seems fair.
So let's get to what I like about these speakers. First up, I tend to focus a lot on tweeters when I listen. The "MCC" Revel tweeter here isn't the best I've heard, but it's impressive. Very nicely extended top end with good delineation and detail. It's got a little bit of "sizzle" and does start to sound sibilant and compressed when you really crank up the volume. But overall, I like that it doesn't roll off the highs and the separation between notes and the "air" was nicely present - better than a lot of speakers at this price point.
Where these speakers shine though is the midrange. The M10 and C10 are 2.5 way designs with twin 3" mid-range/mid-bass drivers and additional twin 3" mid-bass only drivers. Sticking my ear right up against the speakers and hearing each driver pseudo-individually, I found what makes the C10 different from the M10 (other than the position of the binding posts and the little Revel logo on the front
) It seems that the C10 puts both mid-range/mid-bass drivers on the right hand side and both mid-bass only drivers on the left, whereas the M10 vertical speakers have a mirrored placement as you would expect (one mid-range/mid-bass above the tweeter and one below and then one mid-bass only driver above and below each mid-range driver). Having the mid-range drivers both on the right hand side seems to be what makes the C10 "intended for horizontal installation" as Revel puts it.
And this little tweak works! I found that standing above or laying below the level of the tweeter changed the timbre and voice of the M10 vertical speakers - as one would expect with a WMTMW design. But the C10's sound changed much less dramatically when moving side-to-side, which is excellent! The high frequencies naturally rolled off a bit and there was some change to the timbre, but it wasn't anything like putting an M10 on its side. Like I said, a lot of other on-wall systems from other brands are just three completely identical speakers and the center doesn't match sonically when it's horizontal. Revel's simple solution works. It isn't completely flawless, but it's a much better sonic match for anyone who is sitting to either side of dead center.
Now the unexpectedly good stuff. The imaging and soundstage was better than expected. Again, not the best I've ever heard, but better than what I expected from such small, light-weight speakers with such compromised placement. There was even soundstage depth, which really made be pretty impressed!
Again, the big strength is being able to move around the seating area while maintaining very good timbre and voice consistency. With such narrow cabinets, there's virtually no diffraction and very little to alter the sound as you move off axis. You're limited vertically with the M10 speakers, but with the C10, I found I could stand almost on top of the speaker or lay right beneath it and the sound changed very little. In other words, it's a darn good center speaker. It honestly does the job about as well as one could hope for given an on-wall placement.
Voices and guitars especially took on that lovely "uncanny" sense of realism. Revel seems to have focused on getting the midrange right with these speakers and I'd say they succeeded.
The mid-bass though has some quibbles, but I found it's mostly placement related. What I found is that these really are on-wall speakers. The M10 come with some stand options and the C10 comes with a little rubberized "foot". I tried them out with them sitting on the TV stand and the sound changed rather dramatically. With the C10 on the TV stand, there was a slight "cupping" effect to the sound and amplification of the mid-bass (as you would expect from having an additional boundary so close). What made the change stand out was that the M10 sound didn't change nearly as much. With the midrange and tweeter drivers further away from the TV stand boundary, they didn't take on this "cupping" effect or gain the same amplification of the mid-bass. The result was that the C10 no longer sounded nearly identical to the M10 - an effect that I absolutely hate and plagues so many speaker systems.
What I found as a reasonable solution for anyone who might use these Revel speakers in such a setup was to use the smaller M8 speakers for the front channels instead. With the M8s sitting directly on the TV stand, the bottom midrange/mid-bass driver was now just as close as the C10's drivers, so the amplification of the mid-bass was about equal and the timbre matched much more closely than with the taller M10 speakers.
On the wall is where the M10 and C10 combo shines though. With the C10 up off the floor and no TV stand beneath it, its sound really matches the M10 speakers well and I get those nice, nearly flawless pans across the front and no "cupping" effect on voices or mid-bass. For anyone using these speakers on their stands or "feet", I'd recommend using the M8s up front instead and keeping them as close to the TV stand as the C10 center.
So overall? Good speakers. Better than pretty much all the other on-wall alternatives. A bit surprising in that they managed to retain some soundstage depth and a really good sonic match across the front when mounted on the wall. If you were actually paying $500 a piece for the M10 and C10 and $250 each for the M8 though? Hard to say they'd be worth it at that price. They basically sound about as good as normal bookshelf speakers in the $250-$300 each range. And they don't have as much bass extension as any normal bookshelf to be sure. But where the higher price is somewhat justified is the tricky on-wall placement. Mount a normal $500 bookshelf speaker to the wall and it won't sound as good as these Revel speakers - so that's where the value lies.