Using Professional Amps On Home Theater Speakers

Are there any drawbacks other than fan noise to use pro amplifiers on hard to drive home theater speakers? I have several pair of the amp-killing 4 ohm Infinity Kappa 9 speakers that dip down to 1 ohm. To use six or eight of these speakers in a home theater would take a tremendous amount of money to power them sufficiently. There are certainly lots of speakers out there that are waay more efficient, but I already own these and would like to find a solution to power them sufficiently for my home theater. The Kappa 9 are about 85db efficient and suggest an amp of 60-340 wpc.

On the web I've seen a professional amp made by QVC, their MX2450 model is rated at 650 wpc @ 4 ohms and 1200 wpc @ 2 ohms for $750.

The amps will be 40 feet away from the seating area, so fan noise will not be a problem. Black background, liquid mids @ highs, wide and deep soundstage, "air", extended decays and all of the rest of the adjectives to describe a desirable two-channel amp is not important. I just want it loud and powerful. My home theater will be totally separate from my two-channel system.

Please weigh in with your opinions on this.

..thanks, Mitch
Should be fine. If its just for movies and TV, I can't imagine that this would be a problem; in fact its a good solution, IMO. For the use you describe, I think that "audiophile" characteristics are largely irrelevant. We are visual creatures and for me, I've put my $ into the display for my HT. Just commenting on the concept, no knowledge of the actual amps.
The manufacturers list the Kappa 9 as 4 ohm speakers.

My budget is around $10k total for amps to power nine of these speakers for my home theater.
If your budget for the amps is $10K, why not get two Krell TAS amps and have $3-4K left over?

Also, there was a used Theta Dreadnaught at 5 X 200 watts for sale earlier this week. These aren't that great for 2-channel (which you don't care about anyway), but getting two of those dreadnaughts should put you out about $5,000 total for 10 channels at 200 watts into 8 ohms each.

Having a son who is into DJing I have a little (tiny) bit of experience with the types of amps you are referring to. They do fine for their intended purpose, but they are usually "loud" - not just from the fans. They seem to have a greater tendency toward buzzing, humming, etc. . . But those could all be grounding issues. But that would be one of my concerns.

But you could certainly get a stack rack for a bunch of those amps and have them all take up just a few square feet of space. I think most of the current "professional" amps of today are class D and have gotten surprising cheap (which tells us all alot about the "real" value of most class D amps and what it really costs to build them!).

One thing you will need to address with these amps is the types of speaker connectors offered. Many professional amps only offer 1/4" or neutric speaker connections and many also just accept balanced inputs. Both do have real work-arounds, but something to keep in mind. Go to your local Guitar Center and talk to some of the guys there for more experienced input on this.
My room is 70 feet long, 22 feet wide with a 22 foot high

My Room With The Screen Rolled Up

My Room With The Screen Rolled Down

As you can see, this room is much larger than most
conventional home theaters, hence the inquiry into a
commercial application.

Of course the Kappa 9 were intended to be used as front main
two-channel speakers, I've just happened to have managed to
accumulate four pairs of them over the past ten years and
wish to put them to good use in my home theater since I
already have them on hand.
My preference would be Crown or Bryston
I use Alesis RA500 with MMG's. Very happy and no fan. The Crown K2 is supposed to be even better.
Loud isn't everything. The extra volume won't help with clarity. You have to compromise somewhere on quality vs quantity. I've owned clubs and tried those amps at home. YUK!
Keep in mind that bass and the center channel count the most in a theater. I'd buy a sunfire 5x400 or similar or two of them.
The Kappa 9 will bring the Sunfire 5 x 400 to its won't wake up the Kappa 9, they just don't have the muscle at 4 ohms and below to get the job done. I've owned the Sunfire Signature stereo amp at 600 wpc and they performed only satisfactorily with the Kappa 9, I needed two of the Sunfire Signature amps in a biamp configuration for superior results.
Post removed 
70 ft long room. Is that a business,or institution or home? What are walls made of and covered with? Flooring?
Doc, it's a loft that I live and work out of. It used to be
an industrial building before the conversion. Very thick
carpet and padding over a concrete floor..... and ceiling is
concrete also. Walls are drywall with insulation with
neighbors on both sides.
I've not listened to the Kappas and certainly don't know the real power or current they require to perform properly.

Also, I do understand you are just looking for HT sound, not top quality two channel performance.

Normally, I would not recommend a digital amp as I don't think they are very good with traditional driver speakers with regards to two-channel performance (I have never heard a Class D amp I was impressed with for this type of speaker and I have heard many and owned several). For the record, I think Class D amps are best on ribbon and planar speakers - but that's it.

But in your case, and since you don't seem to care that much about the quality, perhaps you need to lean in this direction. Though I have to warn you that my Bel Canto Ref. 1000s (1000 watts at 4 ohms per channel) were not powerful enough to properly drive my Thiel CS 6s while at the same time, my Mark Levinson 334 at 250 watts at 4 ohms did not have any problems in my sized room driving the same speakers.

What amps do other users of these speakers use to drive them? Are these speakers really designed to address that volume of space?

I know when my son DJs and he needs to cover a larger space/volume, he ends up having to use many subs (sometimes 6-8 total dual driver or sometimes quad driver sub/low bass units and is running thousands of watts just on the subs) just to properly pressurize the large room.

Why not go to Guitar Center and talk to the guys. You can rent a DJ rig for a weekend (excluding the speakers) or at least the necessary amps. Guitar Center lets their employees rent stuff privately, so you can probably get away for a few hundred dollars if you are just talking about the amps and the cables. It will give you an idea of what the sound will be like.
Ckoffend, I used Carver Silver 9t monoblocs (900 wpc @ 4 ohms) to power them. One pair of monoblocs did a good job, but with two pair of monoblocs in a biamp config, the speakers take a quantum leap and becomes a totally different speaker in a whole 'nother league. I had five pairs of those monoblocs and sold all of them, they were 20 years old. I suspected things may start to go wrong with them in the near future, so I sold them before they started to fail. The fees Carver charges to fix them was more trouble than it was worth. I also used the Sunfire Signature (1200 wpc @ 4 ohms) stereo amp to power them. I also needed two of those also to get the most out of the speakers...the Carver monoblocs were better than the Sunfire amps. I don't know what they were designed for, but one pair of bi-amped Kappa 9 can fill this room with ear-splitting sound without breaking a sweat with no distortion.

I had considered getting rid of the speakers too because they are so hard to drive.
I'd hate to see your power bill.

I don't dispute the quality of the performance of these speakers, as you seem to be quite enthralled by them.

Perhaps you could consider using these for your fronts and finding alternative speakers for your sides and rears. These alternate speakers are really more support based anyway and perhaps the Kappa's are being "wasted" on the intended purpose and location in some regards?

I got into HT for a while, ended up with 5 Wilson W/P 5.1s, but in the end, I didn't think the rear ones were really being put to good use - especially more so since I am not a movie guy.

Just a thought and it sounds like it may address some of you issues between amplification, speakers, and room fill. Part of me thinks that you are being forced into sub quality amps in keeping your speakers and based on the budget, and if this is the case, I suspect you will be disappointed after spending the money and not getting what you want.

Again, I would start by going to Guitar Center and renting the amps for a weekend, tell them how much power you need - if its 2000+ watts per channel, they'll have it. It will end up being the cheapest way for you to determine if you can go "pro level" amps.
I totally forgot about Carver. 7 old Carver cubes will blow your roof off-sound like crap but wow will it be loud!
I have an original QSC PLX 2402 that's used to power a Bag End 2-10" and an ELF 18". I did use it my two channel system for a few weeks. The PLX series has a switching power supply (not to be confused with class D) that is mechanically noisy for home use. QSC offers a wide range of amplifiers with different power supplies some of which are used in theater applications.

They are physically bullet proof. In the two channel system it lacked a very slight last little bit of finesse with a slightly closed in sound stage. On the other hand the bass weight would compare to the very best in the audiophile world.

Their low cost and customer service is outstanding. Used often in Bass amplification their representative is a fixture on the BassTalk forum.