2. home-theater
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Adding 5-channel amps to AV Receivers

I'm currently shopping for a used 5-channel amp to use with my Denon x3400h receiver with a 5.1.2 Atmos setup, speakers are the older SVS SCS1/SB1 which still do great.  This setup is 100% movies/video games, music is for the 2-channel setup upstairs (Levinson, Revel, PS Audio).  The home theater is never going to get the budget that the music system gets, but its still a lot of fun and Dolby Atmos is really cool with down-firing ceiling mounted speakers.

My question - It seems like adding a separate 5-channel amp to pretty much any AVR would be a very standard setup for anything above a low-end home theater setup, but I rarely see it discussed.  IMO its asking a lot of a sub-$1k receiver to handle all the processing and 7 channels of amplification with its single power supply.  When you can buy a used Rotel, Parasound, etc 5-channel amp for less than $500 and let the AVR be the processor, this should be a no-brainer right?  Pulling out at least 5 channels to a real amp should have all kinds of obvious benefits.  Even if the speakers are not full-size, reasonably efficient, and there's no clear need for more power, this should still produce much better sound.

It seems like an obvious move but its hard to find any discussion of it, usually the conversation goes from budget AVR to high-end AVR to separates.  Am I missing something here?
jimmywho
jimmywho OP
20 posts
 
It’s a huge benefit sonically to add a separate amp, but often it comes down to what needs to be passed over HDMI as that is generally the biggest impediment to AV Receivers and why it often requires upgrading or changing the receiver out before purchasing a multi channel amp.  Also, after getting a new multi channel amp, that will easily lead to replacing the old receiver with a dedicated preamp/processor because though you are bypassing the amplifier section, there are still inherent advantages to having a good pre/pro.  
The difference you’ll hear adding the amp will be just as big or bigger when ultimately switching out the receiver to a good pre/pro.

Great perspective here.  This is still an audio rabbit hole after all, so  there is zero doubt in my mind I'll eventually get a separate processor.  But for right now my home theater priority is getting Dolby Atmos with decent enough sound without spending $3,000.  What baffles me on the current crop of separate processors (and I could be wrong here), is that there doesn't seem to be one that even has Atmos for less than $1,500 or $2,000.  How do the $300 cheap AVRs have Atmos, but it takes $2,000 to get a processor that has it?

It seems like the move is to let the processors come down to earth on price and use the Denon in the meantime.

I actually have another amp on the way, a Krell Showcase 5 which is total overkill but the price was just too good to pass on it, but hey at least there will be zero chance the amp will be the weak link.

mjcmt's avatar
mjcmt
710 posts
 
That’s such a great video, thanks for sharing! For the most part it reinforces my thesis here, that on most sub-$1500 receivers, the amps and power supplies get seriously compromised.

On the other hand, its absolutely crazy to me that it takes a $3,000 AVR before the amps actually turn-off when using the pre-outs, that seems like the most basic function of even having the pre-outs. However, the amps simply being turned on but not actually driving any loads should be far less of a strain on the power supply than having 7 channels going.
Keep in mind that according to Gene DellaSalla that even if the internal amps of AVR are not being used, and still turned on, they introduce distortion into the preamp section as volume is increased, so the internal amps must be shut off like in the high-end Denons. So adding an external multi-channel amp to an AVR is more of transition to having a separate pre/pro and power amp, so factor this long term transition into your budget.

Since I’m not a serious videophile owning a somewhat newer high end AVR is a better choice for me. My 10 yr old Yamaha RXV2700 140 wpc 7.1 avr is a good compromise for me. Stepping up to something a bit newer with high power may be a good alternative to separates.
jimmywho OP
20 posts
 
Keep in mind that according to Gene DellaSalla that even if the internal amps of AVR are not being used, and still turned on, they introduce distortion into the preamp section as volume is increased, so the internal amps must be shut off like in the high-end Denons. So adding an external multi-channel amp to an AVR is more of transition to having a separate pre/pro and power amp, so factor this long term transition into your budget.

Since I’m not a serious videophile owning a somewhat newer high end AVR is a better choice for me. My 10 yr old Yamaha RXV2700 140 wpc 7.1 avr is a good compromise for me. Stepping up to something a bit newer with high power may be a good alternative to separates.
For sure, without question its really disappointing that the pre-outs on pretty much all receivers apparently are not well implemented.  That's a convincing explanation and it does reinforce that adding the external amp is not the final answer, even if its a good upgrade in the meantime. 

It also provides a good explanation for my original question of why this isn't more common, I'm very appreciative for the info here.


ddafoe
241 posts
 
I purchased an Emotiva UMC-200 pre/processor when it came out and paired it with an Anthem 5 channel amp.  That combo definitely out performed an older but higher end Denon receiver that I was using as a 5 channel processor (i.e. it supported preamp out).

I just got my first source (4K Amazon Fire Stick) that wouldn't work with the 6+ year old processor.  I didn't feel like spending a lot on a new processor so I just purchased a refurbished Yamaha TSR-7810 receiver that has a preamp out.   I cabled it up to the Anthem and after running its auto speaker setup listened to a movie soundtrack and I think it sounds at least as good if not better than the much older processor.   I'm definitely happy with its audio quality (as I was with the Emotiva); the Yamaha can be had for $300ish refurbished.

jimmywho OP
20 posts
 
Finally have an update on the results.  Had a couple issues with both amps I bought, but long story short I'm using now using a Krell Showcase 5 amp into the Denon 3400.  I'm only using 3 channels on the Krell for the front 3, and the Denon is handling the rest.  One of the channels on the Krell outputs some static (needs a re-cap maybe?), but I got a great deal on it so I'm fine with this.

Overall, its a big upgrade.  Way bigger soundstage, more transparency and clarity, just significantly better sound.  This is my HT setup and its mostly movies with the occasional concert Blu Ray, so I used Metallica's "Quebec Magnetic" and Mad Max: Fury Road as the test subjects.  

Obviously, the Krell/Denon pairing is probably not a very popular combo. But for about a thousand bucks between the two, its hard to imagine doing better for the money for 7-channel 5.1.2 Atmos.  I'd highly recommend going this route, especially if you have speakers that could be considered at all power hungry.

Want to thank everyone here for their insight on the nuances and mechanics on some of the details I hadn't considered (especially the sub-par implementation of the pre-outs on most receivers).







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