Adding a power amp to a receiver

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  • Andrew Pratt
    Moderator Emeritus
    • Aug 2000
    • 16507

    Adding a power amp to a receiver

    As more and more people look to upgrade their sound systems people often ask about adding a more powerful amp to their system. Quite often this obsession we like to call our "hobby" leads us on a quest to sonic nirvana. As a group we are frequently upgrading our speakers or source components looking for that last ounce of detail. As a result a great many people find themselves faced with a choice as to how they are going to handle the processing and amplification to properly drive those fancy speakers we just bought. There's more then one school of thought here with those proclaiming that today's high end receivers offer all the latest decoding formats and all the power one could ever need while others declare that receivers can't possible sound as good as a separate amplifier and separate pre amp processor. Which is right often depends on which side of the fence you sit Lately however there have been a lot of people that have decided to opt for a more compromised solution and are simply adding an external amplifier to their receivers. In many ways this gives you the benefits of the stronger power amp and the affordability of the receivers processing. Of course the big question is does it work? From all the threads that have been posted over the years from people that have added amps and heard benefits and from my own experiences I have to say the answer to that question is a resounding YES. Now some of you might be saying why would adding an external amp that's only rated for 100 watts per channel improve the sound over the amps in my receiver that are also rated at 100 watts per channel? Well there's more then one answer to this complex issue but first lets look at what rated power means. First off there are a variety of ways to measure how many watts your receiver or amp can provide your speakers, essentially it should measure the amps power output across the entire audio frequency (20 hz to 20 khz) at 8 ohms when all channels are being driven at the same time. Unfortunately a number of companies only measure one channel driven or at 1 khz which is easier to drive then the full audio spectrum or they'll measure the output at 6 ohms which boosts the results. Ideally also they should publish the power output at 8 ohms as well as 4 ohms and in an ideal world the rating will double at 4 ohms over the 8 ohm rating. This indicates that the amps power supply is of a very high quality....however in the real world this seldom happens with amps that are priced in most peoples budgets. So now that we know that manufactures are sometimes somewhat deceitful on their receivers power output we might be able to suggest that just because your receiver is rated at 100 watts per channel doesn't mean it is capable of providing that much power. This site here provides us with the bench tests of dozens of receivers and as you can see there are very few that actually provide the wattages they claim to be able to provide. Power amps on the other hand are almost always measured with all channels driven across the full audio spectrum at 4 and 8 ohms (and often 2 ohms) Also true separate amps often surpass the rated power output as is the case with the HK PA5800 which is a budget 5 channel amp from Harmon Kardon. Its only rated at 80 watts per channel but bench tests indicate that it easily provides more power then that. See here for details on the HKPA5800
    One must also remember that not all watts are created equal. Different amps of the same wattage will sound quite different from one another depending on a number of factors. By choosing an amp that compliments your room, speakers and processor you should be able to tailor the final sound to one you find pleasing. Unfortunately its difficult for us to tell you what you'll like since we're all individuals but that is not to say we can't make some educated suggestions on which amps to try first or which to avoid completely based on its design etc.
    So if you've gotten this far without falling asleep give some thought to adding a power amp to your system and see what benefits you find. If you have a good relationship with your dealer or have a friend with a good amp maybe try and borrow one for a demo...just be forewarned you'll likely really like what you hear

  • Robert George
    Junior Member
    • Feb 2002
    • 1

    I have some experience in the area recently. I am convinced that there is an acceptible middle ground between receivers on one side and fully independent separates on the other. I posted a "little" piece on this on HTF a few days ago and would like to share it here as well...

    There has been a war fought in the audio trenches for years. The battles have been bloody and the losses have been high, yet the war drags on. Of course, I'm speaking of the war between "receivers" and "separates".

    On one side, the "separatists" claim sonic purity, improved dynamics, and greater flexibility. The "Receiverites" claim equal or better sound on a dollar-for-dollar basis and more advanced features for less money. This war has reached a level of stalemate due to the fact that both sides are (mostly) right. Is it then possible to ever reconcile the do-or-die hardcore in each camp? Well, maybe....

    In the true spirit of diplomacy, I think I have found a comfortable middle ground where one can have the best of both recievers and separates. Add a dedicated power amp to a receiver.

    Now, I'm not going to try to tell you I invented this solution, and certainly this will not be a panacea to cure all ills. I have seen others heralding the benefits of adding a separate power amp to a receiver for quite a while, usually getting their voice lost in the din of the "receivers vs. separates" battle royal. And, no matter how good an amp, it won't make a cheap (read; shitty) receiver into anything it isn't. On the other hand, if one starts with a good receiver, adding a separate amp to a speaker system that is not capable of resolving the nuances of sound between the external amp and the receiver is a waste of money.

    So, with that very large caveat that all the components in the system will affect the outcome, I'm here to tell you it is definitely possible to get the best of both separates and receivers if one is willing to concede the inherent advantages of a dedicated power amp for driving quality speakers AND that there are receivers out there that are at least equal to, and in some cases better than, pre/pros costing much more.

    Case in point. I have a Pioneeer Elite VSX-49TX receiver. The latest and greatest from the Land of the Rising Sun with full THX Ultra 2 certification and processing, automatic room equalization, very high quality component video switching as well as video format conversion. In short, this shiny black jam box has stuff even $10K pre/pros don't. And it does what it does very well.

    Don't any of you hardcore separatists try to tell me a receiver can't sound as good as a equivalently priced pre/pro because I'm going to tell you to prove it and you won't be able to. However, I will concede that the one major shortcoming of even this state-of-the-art receiver is the amplifers built in. While I am absolutely certain that a well-designed receiver can bring a level of performance to a modest system that could only be exceeded by spending considerably more money on a full-blown separates system, not to mention the convenience and ease of use for the non-technophiles out there, I also now know with certainty that once the price/performance of one's speakers exceeds the price of the electronics in the system, no receiver's amps will do them justice.

    Continuing my case in point...

    I have had a hardon for B&W speakers since the first time I heard the venerable 801 many years ago. You remember that funny looking one that looked like stacked boxes with the little tweeter cube on top. Obviously, everyone's tastes in speakers will vary, but to my taste, the B&W Nautilus line is simply the cat's meow. I have reached a point in my life that I can justify the kind of fundage that it takes to put these beauties in my living room. Just barely, and I still can only wish for a pair of N802s, but I am the proud owner of a pair of N804s and, just recently, the baddest center channel speaker on the block, the N-HTM1.

    I have now had two top-of-the-line receivers hooked into the B&Ws. It took me just under a year to figure out that even the very highly rated B&K AVR307 nor the 49TX were doing these speakers justice. I finally started paying attention to those smart guys that figured this out before me. Time to get out the checkbook/credit card/whatever and get some real ampage for my speakers.

    The first step was a tentative one. I bought a used 2-channel audiophile quality amp, a Sumo Andromeda, from a friend. My thought was it would take the obvious strain off the receiver allowing the other channels to be driven more efficiently and it would provide me with true "separates" sound for music, which I listen to in 2-channel stereo exclusively. That was when I had the smaller HTM2 center speaker. After trading the HTM2 for the big brother HTM1 last week, I couldn't stand the thought of powering a two thousand dollar speaker with a receiver. The solution was a solid 3-channel amp of sufficient quality to bring out the potential of the B&Ws. I selected the now-discontinued Acurus A200X3.

    Acurus amps are (were) the "budget" line of Mondial, if you can call a $1500 amp a "budget" amp, whose flagship Aragon amps have a well-deserved reputation for stunning audio performance. The Acurus line share a common design philosophy with the Aragons, and hence a similar sound, though without the esoteric level of build quality and esoteric price tag.

    I found a close-out deal on a new A200X3 for under a grand ($999 actually) so I leapt upon it. Hats off to Bob at Avalon Audio ( for terrific service and a special thanks to UPS for screwing up and delivering the box a day early. Overnight service for the price of 2-day. Cool.

    I actually went to work late (with permission) so I could set up the system and do some listening right away. Once the amp was wired in, I sat down to recalibrate and was greeted with my first surprise. Not only did I have to reduce the levels of the front three channels (expected), I had to rather dramatically reduce the level of the side and back surrounds which are still powered by the 49TX. It seems the power supply of the receiver performs considerably better when it is not under any sort of strain. Duh.

    After lining up everything, I was treated to the next surprise, and I have yet to wipe this silly grin off my face. This receiver controlling this amp driving these speakers is something I was not prepared for. Frankly, I did not expect much real improvement in sound quality beyond having more power for demanding soundtracks. What I have gotten is a top-to-bottom overhaul of my entire front soundstage that has thrilled and amazed me. Now my B&Ws sound like what I paid for them. Well, actually they sound like more than what I paid for them.

    The forward soundstage has taken on a clarity, depth, and breadth that I would not have thought possible. And that for stereo. With 5.1 soudtrack material, the improvements are at least as apparent. The sheer effortlessness with which even the most ddemanding soundtracks are reproduced, even at reference level, is stunning. Dynamics I never knew were there have me in a position to have to become acccustomed to a completely different kind of sound. Along with the incredible clarity and detail is a smoothness of sound that allows for very comfortable listening at much higher levels than before. I suppose this is what happens when one feeds this kind of clean power to a good speaker. There is no trace of harshness or gritiness in any register. Just smooth, clean sound with great delicacy and subtlty on the one end and serious slam on the other. I am truly amazed.

    Now, before you separatists tell me I should just buy a pre/pro and an amp with a few more channels, I will direct you to the Pioneer website (VSX-49TX). Find me a pre/pro that does all that for $2400 because that's what I paid for the receiver.

    And for you guys with receivers that are thinking you don't need a dedicated amp, well, maybe you don't need one. Or maybe you do. I didn't need the Acurus amp for my front channels, but then, I'll never go back to "just" a receiver ever again.


    • Uncle Clive
      Former Moderator
      • Jan 2002
      • 919

      Hmmm, thanks errr George for your testimony. I am not sure if anyone here has been bashing the "reciever/separate world but for me this was a simple quest for knowledge. Has I/we grow, we become more and more enthusiastic and demanding. Hence, our theaters and listenning habits not only differs from others but go through radical changes as we grow and that's where I am at.

      I am a rookie and I am saving myself costly mistakes by sourcing my concerns here. I don't want to run out and by a amplifier/s to add to my system before understanding how the whole thing works. Now you've raised a very interesting point about having real good speakers to reproduce quality sound. This is good meat.

      Thank you much.

      Andrew: You also have been a great help. Thanx for moving the thread and for the links. Thanks!


      HEY!! Why buy movie tickets when you can own a Theater?

      HEY!! Why buy movie tickets when you can own a Theater?


      • John Holmes
        Moderator Emeritus
        • Aug 2000
        • 2703

        Wow! Between Andrew and Obi it's pretty much covered. Great info guys.

        "I came here, to chew bubble gum and kickass. And I'm all out of bubble gum!!!" My DVD's
        "I have come here, to chew bubblegum and kickass. And I'm all out of bubblegum!!!"


        • Andrew Pratt
          Moderator Emeritus
          • Aug 2000
          • 16507



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