Ok, the Philharmonic thread has made it harder to decide. Would I need a sub with the Philharmonic 3's? This is really hard....
All stereo box speakers will need subs if you like accurate, controlled response 15hz - 100hz, because of the room.
Even aside from flat response, even if the Phil 3s hit 25hz which they do, they are only 85db sensitive.
If you look at a movie at reference, LFE normally means ~115db @ 3m capability and front speakers should be cruising along @ 105db @ 3m
The Phil 3s, with a 300w @ 4 ohm amp, will deliver about 97db @ 3m
Now for the most part that's probably "fine" but really I'd leave those speakers for music listening. That's a lot of demand to be putting on speakers and I really don't like the idea of running speakers near and possibly beyond their limits.
The CBT36s with a 500w @ 4 ohm amp, will deliver above 107db @ 3m over the bass region at least.
Obviously at 97db they are less strained, as they need only 50w @ 4 ohm to do it.
Watts aside, neither speaker is likely to be very composed 15hz - 80hz at those kind of SPLS. You really need subs. Multiple, highly capable subs. Yes for classical music the Phil 3s will shake your room and reproduce pipe organs etc but that's a totally different deal from movie LFE. Besides movie LFE there's also the matter of flat response that I mentioned earlier, and you'll be limited by what stereo speakers can do in your room from a flat response perspective.
I'm not saying the Phil 3s aren't a great speaker but I'd definitely lean towards the CBT36s for movies, although they will sound just wicked for music even at low levels. Now if it's not a high end HT, but just a living room where you critically listen to music and watch some TV, or a dedicated music room, then the Phil 3s make perfect sense
Both are... extremely good speakers.
