What Power Amplifier Should I Buy?

Well, if you want ruler-flat response and headroom, your choice is made for you: professional studio monitors, not audiophile-focused speakers. Audiophile speakers typically have woefully low efficiency, 85 to 88 dB/meter/watt, which is frankly as low as it gets. Worse, the well-known audiophile speakers that get glowing reviews in the glossy magazines also have wacky response curves, which is the worst of both worlds ... low efficiency and boom-and-tweet responses tuned to reviewer’s tastes. Not going to name them, but they’re the brands that appear in $100,000+ systems and are owned by the reviewers.

You don’t want either: ergo, avoid products marketed to audiophiles. I would recommend pro monitors made by UK and European companies, which sometimes have amplifiers built right in ... amps of very high quality, considering the intended market. They have tons of headroom and do not require equalization, and make audiophile speakers sound like a joke. I’ve heard them, and they are very very good.

My personal favorite horn speakers are the Joseph Crowe speakers made in Canada, which have modern horns with flat responses and low energy storage. They’re basically the modern successors to famous vintage speakers like the Altec 604 Duplex and the Valencia and Model 19 (which have devoted followings to this day). I greatly admire Joseph Crowe’s work ... modern, comprehensive engineering, and zero marketing BS. And they are stunningly beautiful as well.

I’ve migrated to the horn camp over the last two decades, but only consider modern computer-designed horns, not the awful horns of the Fifties and Sixties. They combine effectively unlimited dynamics with silky-smooth sound and accurate, electrostatic-like transients. A correctly designed horn should require very little equalization.

Not cheap, though ... the horns alone are thousands of dollars.

@lynn_olson 

Thanks for the recommendation.

Gee, those are some expensive speakers. My budget is $5K. I need to stay near that price.

What is your opinion of the Revel f208 speakers? I bought them mostly because I liked the small bookshelf speakers they make (now in the lo-fi TV system that my SO likes a lot) and by Amir's g;lowing review on ASR.

Not interested in Revel, sorry. I would take Amir’s subjective opinion with a grain of salt, for the simple reason I have yet to meet any reviewer that has the same tastes as I do. I’ve been to their houses (not Amir’s) and didn’t like any of their systems. I don’t trust anyone’s subjective reviews. I'm out of sync with most of the industry.

However, that said, Amir’s measurements of pro monitors are right on the mark. Consider those first. They will have better dynamics than audiophile speakers.

I should mention there are hard limits on the dynamics of a 2-way speaker with a 8" woofer and 1" dome tweeter. The only dynamic step upwards is a 3-way with a 10" or 12" woofer, 4" midrange, and 1" tweeter. But ... unless superbly engineered, 3-ways usually have a poorer sense of coherence, or integration, than a 2-way speaker. A good 3-way is actually extremely difficult, particularly at a moderate price point.

2-ways are far easier (speaking from experience here). A good crossover and well-chosen drivers, and off you go. But getting coherence out of a 3-way is often difficult, because the midrange driver doesn’t quite match the sonic character of the woofer, and worse, the low-frequency crossover falls in a range where subtle differences in timbre are definitely audible. This is why 3-ways at audio shows often sound disjointed and incoherent, instead of like a single source or like a real musical instrument.

A (very) common problem is the 3-way will sound "right" and coherent at a fairly loud 85 to 90 dB show level, but disjointed and confusing at a 65 dB background level. Something to beware of in show demos ... how do they sound when the playback level is moderate? Is the speaker suitable for background music, or not? Big, complex, expensive audiophile speakers often fail this test.

So the choice between a 2-way and a 3-way isn’t as simple as it first appears, depending on your personal tolerance for incoherence. Once you learn what it sounds like, you can never unhear it, and your choice of acceptable speakers narrows quite a lot.

Historical note: Altec always designed 2-way systems if they had any choice in the matter, while JBL leaned towards 3 and 4-way systems. Part of the reason why the midrange is so different between Altec and JBL in their big monitors.

The brands I think of are horrible choices: ZU Audio and Klipsch.

@kevemaher I don't see any problem with the ZUs. They easily keep up with the studio monitors @lynn_olson was recommending. The Klipsch, harder to say; if you want the most dynamics you get one of their horn systems but as far as I can tell they are (IMO) entry level to horns. I should qualify that by saying I've not heard a set in a controlled environment for quite some time. I would not be surprised to find out they are using computer optimization in their horns- anyone who doesn't do that these days is missing a bet!

I'm a fan of horns also; they have controlled directivity so can be used to minimize side wall reflections which otherwise contribute to harshness and of course they are much easier to drive!

You might consider a set of Deadalus loudspeakers which are typically about 95dB (meaning you'll need about 1/10th the power to get the same sound pressure in your room as opposed to the speakers you have now) and are reasonably priced. There are plenty of other choices.