What Power Amplifier Should I Buy?

@lynn_olson 

@atmasphere 

My thanks to both of you. I agree with all that was said. I agree my speakers are mostly 4 ohms. My previous measurement indicated that even for the 4 ohm load, the voltage I measured at the speaker input terminals (pink noise input) was 3V. This is 9/4=2.25 W. The amp is rated to 180 W at 4 ohms. This is why I've given up the search for a new power amp.

I agree that higher efficiency speakers will provide more headroom.

The brands I think of are horrible choices: ZU Audio and Klipsch. I want a more neutral speaker, not these.

I've not based my speaker searches on efficiency, rather I chose a speaker that was neutral.

Can you suggest a brand that might be more neutral?

I have an FR curve from my last tuning. And I have just discovered what a pain it is to upload a jpg into this forum. So I won't. I'll attempt to describe it to you.

I tuned the FR to have a 1 dB/octave slope from 20-20K Hz (actual REW calc is 1.23 dB/octave). There are no big dips. Deviation from the 1 dB/octave slope is +/- 5 dB maximum throughout the spectrum. The phase plot indicates a problem (room resonance) near 300-400 Hz. But otherwise it is well behaved. I consider this a pretty good FR. I enjoy the sound. My measurements were done at about 85dB SPL, which is near the SPL I normally use for music. And I am evaluating the FR using the VAR filtering REW offers.

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.