Originally Posted by Stereodude
Which pro amps don't have fans?
Pretty much all of them do, and generally are quite audible. I was just saying this as a reminder.
The first gen XLS series are actually very decent in terms of noise.
There is no longer a 2u "requirement" for the latest "class D" designs, but it depends on how much power you want.
Someone mentioned powersoft as a 2u amplifier which can be very pricey but often times the comparison is not apples to apples since powersoft often have WAY more transient power.
Another option is Lab's IPD series for more typical amplifier requirements. The control capabilities of these things are fairly powerful but mostly for pro-applications.
The NAD M27's that I used to replace my crown XLS's with are now fanless and Hypex nCore based. These are quite cool also even in with a stack of 3 of them. They also have 12v triggers which is nice. These things come with 7 channels per box. Unfortunately they are not rack mountable unless you buy some middle atlantic custom racks which aren't exactly cheap. They do look slick in a rack though. The sound quality, especially noise floor characteristics simply blow away the crown xls line for high sensitivity speakers. You can hear ALMOST no hiss out of these things even with high sens. speakers. Unlike the crowns, they do not have any high pass filters or volume attenuators. Because these amps are so quiet, I did not feel the need to use volume attenuation tricks with the NAD's in order to lower the ambient hiss out of them.
The M27's are considerably pricier but definitely better than the first gen Crown XLS's in my application.
I actually considered doing a custom build project with everything I wanted: 12v triggers, ncore modules, low rack space requirement, neutrik speakon connectors, etc. Unfortunately there was no rack mount / pre-made casework available and the cost did not make sense at that point compared to NAD's fully functional new amps.
For main speaker amplification, I went with the new Benchmark AHB2, the lowest signal-to-noise ratio amplifier built so far. This thing is simply the best amplifier ever made in terms of baseline ambient noise. The sound is very similar to the Pass Labs series amps that I have used such as the XA30.5 and XA30.8 while being completely black in terms of noise. The NAD ncore setup is very good also, but not quite as quiet as the Benchmark AHB2. The ncore is slightly brighter in comparison and with my particular speakers, a bit more fatiguing over time. With different main speakers, I might prefer the NAD's "more detailed" top end. In either case, the AHB2 now powers my main speakers and the NADM27 handles the rest of the 17 channels of surround duties.
I will likely add 4 more speakers with the rest of the NAD's channels if I feel it is necessary to complete the Atmos/X surround field.
My experience with the first gen crown xls series for surround speaker duties was quite good. I would not say that ncore based NAD's are some sort of mega game changer for most people. In fact, for most folks looking to do a 20+channel system, the Crowns are considerably more cost effective.
If you haven't tried to setup a "mega" multichannel setup yet, I can tell you there is some seriously awesome fun to had. Crowns represent some of the best amplifier value out there in order to get high channel counts.
My wishlist for the 1st gen crowns could be summarized:
1. I didn't like the styling much but this is not critical.
2. The volume knobs, while functional could not be locked into position (such as what a Lab Gruppen can do).
3. the noise floor was really really bad for high sensitivity speakers such as my mains. The NAD's definitively blow the Crowns away in this department.
4. I do love neutrik speakon connectors and I wish all manufacturers of all amps and speakers would move to these. But we know consumer manufacturers are half insane. Dual pole connectors on the Crowns were awesome and these are also present on the Benchmark AHB2.
5. 1u rack space is technically feasible for these but they went with 2u perhaps to make them "look beefier"? Perhaps they wanted simpler cooling size.
6. 12 volt triggers are lacking in the crowns and are very important if you want to be able to turn them off easily with your other stuff. having 10 amps all go off at once using external 12 volt trigger strips, etc. can lead to these tripping your rack's breakers. You could alternatively leave them on all the time and burn some electricity. I like them off during listening to my mains for music since the crown XLS + marantz 8801 hiss too much.
7. A 4 channel version of these would have been decent in a 4u space.
8. IP based control of all the crowns would be nice but that would get you into the price range of lab gruppen.
I do use a Lab Gruppen 10000 PLM for my subwoofers for a simple reason. I asked Notnyt what brand amp he would use for subwoofers if cost were literally no object and he said a "real" lab gruppen (as opposed to the clones out there). The Lab Gruppen has some loud fans but this thing is crazy powerful. I am fairly certain this thing could melt my subwoofer setup if I pushed it even a little bit. During normal usage, I am using less than 25% of its peak capabilities I think.
The Lab Gruppen is some of the craziest amplification in a 2u rack space besides the powersoft products. The Dolby Lake functions are also awesome. I was able to integrate this into my control4 system for power on/off functions also with some effort using their hexcodes transmitted via IP/UPD port.
Another reminder I just thought of: Some of QSC's products have 4 channels of amplification in a 2u rack space and also have more DSP capabilities. The QSC stuff looks better too... The QSC pricing per channel may be a little more in line with what most people are looking for in a Crown XLS.
I think you get a sense for what kind of amps I would like to see personally for large scale multichannel setups: Hypex ncore modules, pro connectors, pro DSP, fanless, 12v triggers, compact rack space usage. Perhaps, even Tascam balanced connectors the way Datasat and Trinnov gear is setup.
I feel that the "pro" gear and the "consumer" gear should have converged long ago with each having all the benefits of the other. The Benchmark AHB2 gets very close to my theoretical ideal but is pricey to be doing multichannel with it.
Hopefully this detailed description of my experience helps