Studio/Performance Amps for High-End Systems?

As a practicing (hobbyist) keyboard player and audiophile, I am familiar with why one would not use a guitar amplifier for a keyboard, for example. But, I notice that some of the finest brands of high-power power amplifiers for recording studios or live performances (QSC, Crest, Crown and more) cost hundred or thousands of dollars less than high-end "audiophile" power amplifiers of similar or fewer watts/channel. The specs of these musicians' amps, designed to play 20-20K full-range sound through very low impedances (often as low as 1 ohm) seem to equal those of, say, a McCormack, Classe, Krell amp.
Is there something I'm missing here? If one needs 500 wpc or more, why buy a McCormack DNA-500 for $7K when you can get a QSC with 800 wpc into 8 ohms, capable of driving a 1 ohm load, for $2500?
Is there something I'm missing here?

Amps for studios tend to be very precise.

Amps for high end audiophiles tend to be "softened".

Crown and Bryston are are simply excellent amps but the harshness you get with precision is not necessarily what domestic owners like. Some will claim it is distortion from SS high power designs and high amounts of negative feedback but I think it is more a factor of designs slightly tailored to cater to the tastes of the two camps. (Precise "you get what you get" versus a more relaxing laid back or "musical" sound)

Some audiophiles will complain that studio gear sounds like a PA. On the flip side, studio professionals will often complain about the coloration introduced by home consumer systems.

Audio engineers will often spend time listening to their mixes on "dumbed down" consumer systems rather than rely on just the studio sound. this is in order to see how the mix "translates" to the widest audience.

So what you get on most commercial recordings is dumbed down (especially dynamically) from the real thing anyway.

If your tastes run towards the precise approach then you are lucky because, indeed, some pro gear is good value compared to audiophile designs. However, teh converse is also true...some pro gear is stratospherically priced and many top studios are well over $1 million invested in gear/acoustics.
A lot of "stage" gear, not necessarily "studio" gear like Crown, QSC and Crest have higher distortion allowances. They are designed for volume and abuse more than quality. Also, the cooling fans in them are usually unbearable for a home system. I've got several at home for my whole house system and they are crude compared to my other gear. Even the connectors are not gold plated and usually are 1/4 jacks or balanced, not RCA.
I'd take my 20 SET tube amp against my 300 watt QSC any day!
I think it tends to be presentation. Every pro amp I have ever had in my systems has been forward and dynamic, but ultimately fatiguing.

With this said, in the right system pro amps do offer a heck of a lot of value.
More expensive amps are more expensive either because...

1) they use better parts/designs, thus cost to manufacture is higher
2) are produced in lower quantities, thus economy of production is a factor
3) are sold by companies that want more profit, so they sell them with higher margins (not a negative thing, nature of capitalism and allowing there to be products for everyone).

Your question is vague, though. When you say "pro" that is not an all encompassing defining label for all people that are "professionals" or make money in the production of music or sound for video/film. Some people would like to equate audiophile being equal to consumer, but that is simply not the case. There are audiophile professionals too.

There are many different factors to consider when quantifying an amplifier's performance, and absolute power output is just 1 factor amongst many. There are functions like THD, slew rate (very important in my mind), and as others have mentioned, heat / noise / efficiency considerations.

Audio equipment has many parallels to the watch. It is a synthesis of functionality and also as a piece of jewelry. Each person can make their own evaluation of what they need and how they will spend it. Some people might need the advanced functions of an aviators chronograph, while others like it just because it looks cool. There is nothing wrong with either viewpoint. Just realize that the line drawn between consumer and professional is more of a marketing demarcation than one of a technical division. Some consumers have become very good listeners and many professionals are much less concerned with accuracy than their target audience - just because of their expertise in engineering pleasant sounding pop/rock for the masses. To say that pro audio equipment is exempt from the "equipment as jewelry" effect is of course just not true.

At the end of the day, you have to make an informed decision as to what equipment to buy based upon its technical merits in your system. This might involve research and testing, or it might be based upon "word of mouth" or following in the footsteps of others... or maybe even based upon one being swayed by glossy advertisements. There are many multitudes of lemmings in both the consumer audio and professional audio markets that fall at all levels of the spectrum of informed / uninformed.
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Pro amps like the ones the OP mentioned are designed for power and reliability at the expense of sound quality. They are not "accurate" so much as they are crude, due to the use of lots of negative feedback or digital supplies and output stages. They often have connectivity, controls and features that complicate them compared to amplifiers designed for purity of sound.

In recent years, more and more of the Pro amps run efficient classes of operation such as class D or, when conventional, are biased more toward class B for cooler running and efficiency rather than good sound. In contrast, the most desirable and good sounding audiophile amplifiers run in Class A or are biased toward class A and attempt to minimize or eliminate the use of global negative feedback. Some innovative class D amps have even begun to appear in the audiophile world, but they have not had wide acceptance thus far.

Parts quality in Pro amps tends to be poor when compared with audiophile amplifiers. Pro amps often use generic and inexpensive parts everywhere including critical signal locations. Many audiophile amplifiers have better quality parts in their power supplies than pro models use in the signal path.
I might hurt people with the following statement, but I'm afraid this is the truth: Proamps are NOT audiophile quality amps with the exception of two brands: FM Acoustics from Switserland and Rey Audio. Sorry.

Good points. Pro amps cover two markets => venue sound reinforcement and recording studios. Only the studios will go for the higher quality sound (similar to audiophile except slanted towards precise/forward sound) whereas the sound reinforcement and music store rental gear tends to be low cost highly reliable high power but lower quality sound.
Elevick/Tsvisser/Davemitchell have all made excellent points. I've worked on High-End and pro gear for years, and have yet to see the pro gear built with the quality of components(passive or active) that are utilized in High-End audio equipment. That's why the stuff sounds electronic, fatiguing, recessive, etc, in the home audio system: It's largely built for brute force and ruggedness. I always recommended Crown for professional installations, but their gear sounds like... well- forget about it for home use! Some of the studio gear being the exception(I'm using a Hafler TransNova 9505 to bi-amp my woofers). Then again- If you can listen to the pro gear and not be bothered by the sound: Enjoy the savings!!
Pro audio power amps are only good for... bass amplification :)
I stand by the statement
Some audiophiles will complain that studio gear sounds like a PA.

Those who categorically dismiss all pro power amplifiers are simply showing their prejudices. The truth is they tend to sound quite different because they are targeted at different types of listener. Huge power is often necessary for realistic unclipped sound reproduction on studio music that has not yet been dynamically compressed/squashed for consumers. Most audiophile speakers would not last five minutes in a studio before the tweeters were blown and the power amp output transistors fried.

I've worked on High-End and pro gear for years, and have yet to see the pro gear built with the quality of components(passive or active) that are utilized in High-End audio equipment.

Then you have simply not come across EMMLABS and other high-end pro gear with similar quality build to high end audiophile gear.
Shadorne- I'm certain there are quite a few brands that I've not worked on in the past 28 years, and you're correct: EMM Labs is one of them. Meitner has been designing High-end audio for years, so I'm not surprised he uses quality components in his pro gear(and charges accordingly). His DAC8 MKIV brings five figure prices. There aren't that many studios that can afford that for one piece of gear. Actually EMM builds more audio pieces than pro. Their two-box CDP/DAC is into five figures as well(like 11.5K, I believe?). Nor have I had occasion to do any repairs on John Oram equipment(I mix on a custom 48 channel BEQ-PRO) . Perhaps that's because there are so few of either in Florida, Ohio and Indiana. We're not talking Crown, Behringer, Marshall, Peavey, QSC, Mackie, Nady, or comparing apples and grapefruit now- are we?
EMMLabs is used by as James Guthrie (Pink Floyd sound engineer).

Here is a list EMM Labs Users

I agree about Peavy and others you mention - these are high power but low quality stuff and have a "PA" sound.
Like I said: It's a short list(BUT an excellent one). The only one in Indiana is Sony DADC(Terre Haute). I've cherished the output of 20 of those studios/engineers on the list for years.
ATC, Bryston, Manley and EAR make amplifiers suitable for professional and audiophile applications. Also didn't Boulder start out making pro-oriented amps.

I agree with the tone of Shadorne's comments about audiophiles wanting a softer presentation than what is useful in a studio environment.

As an aside, there is a school of thought that takes the position that power amplifiers, while important, just aren't that critical to getting high quality sound. Peter Walker of Quad and Siegfried Linkwitz are prime members of that school. Historically, at least for solid state designs, amps didn't become important until Apogee came out with their sub-2 ohm speaker designs. It was then that you saw an explosion of pricey, high current designs and people started to talk about how amps sounded.
Onhwy61- And which of those companies offers a 500wpc power amp for $2500.00?(Read the original question) I know beyond doubt there are a lot of people that are happy with a "softer presentation" or a "warm, sweet, fuzzy, tubey" or whatever sound from their equipment, or that can be satisfied listening to PA gear. I'll never tell someone what makes them happy in their listening room is wrong. Like I said: Enjoy the savings.
As a fellow pianist (and keyboardist/electronicist), I'm interested in this, but from a slightly different angle: I'm interested in using home speakers in performance. The ultimate goal is a higher-quality sound that fits in acoustically with other instruments, even though the source may be a keyboard or laptop. This motivation has resulted in things like this hemispherical speaker:

I'm wondering if a Ohm Microwalsh, for instance, could be driven with a small instrument amplifier (Acoustic Image?).

Any thoughts?
Why? There is definitely a compromise using an instrument amp. The little things like RCA to 1/4 inch adaptors for the jacks will degrade the sound more than you think, especially balanced to RCA adaptors (different impedance).

I owned some fairly sizable clubs and have played with Crown, QSC, Crest and more. Amazingly abusable but that's it. Yes, if budget is an issue, a $300 used Crown will give a lot more volume than a $300 audio amp but at a great expense...Inexpensive studio speakers are the same way, lots of volume but harsh and lacking in the very highs & lows and definitely not smooth. Yep, you can get custom designed ones from companies such as JBL which cost a fortune but are amazing sounding.