...By experience, in no way 150watts is good enough for this range of speakers (and I do not play loud). The same probably applies to C4s as they are not known to be efficent speakers...
Nope, reality can't agree with that. More stuff in the signal path equals worse sound...just louder. Adding more output pairs REDUCES WHAT DISTORTION? You DO NOT need VOLUME for detail! Leaves blowing down a street on a fall aren't loud, and sound glorious! A speaker that needs LOUD to have RESOLUTION has a BIG problem (it doesn't have any resolution!). Where is even 150 Watts in shuffling feet and rustling leaves, the cough in the Audience, the breath of the composer gliding across the microphone? You don't need a gorilla to make those sounds in real life to hear them, and a good speaker doesn't either. Micro dynamic details CAN NOT be forced. You have it or you don't. It's there or it's just LOUD.
Sure, I hear people "repeat" the more power with the C4's. I listened for six hours two times in a row with 150-watt amps and there was ZERO problem at 85 SPL average in a BIG room (better than 4,000 feet squared). The speakers are 89 dB SPL sensitivity, which not exactly terrible. So I didn't not "hear" the party line, I HEARD! The C4 series II and report they have GREAT low SPL resolution. Yes, they go way loud with 150 watts. What impressed me about this speaker was the sound as it was humming along at maybe 70 dB SPL!! playing Dire Straights. Open, clear, full, solid imaging...simply amazing. They refuse to close-up or lose dynamics at low SPL's. THAT is the mark of a good speaker. Yelling teens trying to sing on who has talent need not apply. Paul Simon on the other hand...delightful.
So go as big as you want on the amp, but a smaller simpler circuit will give better sound all things being the same. You don't keep jamming a signal through more stuff and keep things intact. No, never, ain't going to happen. You are heading in the wrong direction, and one that is expensive to "force" good sound out of. It's like a 4,000-pound Mercedes can be made fast (and expensive!), but what's the point when a smaller car does it SO much better?
If a speaker can't play softly, I have learned to pass on them. NOTHING will fix their musical noise floor. No detail doesn't just appear when you turn-up the volume, you're listening to something LOUD, but it isn't detail. I wish LOUD fixed detail, I'd have a bunch of CD's to fix that way!
I'll probably be using ODYSSEY KIZMET mono amps for the sound at the price, but I will NEVER defend bigger is "better" at resolution and detail. It just isnt so at the very best level of perfection and micro dynamics and detail.
The same can be said for speakers, all things being the same efficiency equals WAY less intermodulation distortion and cone break-up. And, those 10-35 watts class A thresholds in A/B amps hum along 90% of the time. You got to like that.
Yep, there are trade-offs with Tube amps and super efficient speakers (Coincidents and such)
mainly dynamics in the bass. But you can not argue the superb midrange micro dynamics in a good tube set-up, where MOST of the music is, even though most of the power isn't! A tube's audio stage is about as simple as it gets. Tube music floor detail is impressive but alas, the systems that get you there are too aggravating day-to-day. Maybe when I retire I'll have time to futz with that.
For now, A click and play out of standby mode system is more appropriate, with exquisite low volume capable speakers.
