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2-channel power amp recommendation
tgadd0
post Jun 23 2012, 01:00
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First, let me open this post by stating that I fully agree with Peter Aczel when he says "any two amplifiers with high input impedance, low output impedance, flat frequency response, and sufficiently low distortion and noise will sound exactly the same at matched levels if not clipped." I'm not looking for a stereo amp to do something funny to my soundstage, or whatever. I also have an excellent pre-amp/DAC/headphone amp which I also use to switch sources and paid way too much for, and good quality sources. I'm primarily looking at 2 amps on Amazon right now, but they have some features I don't need, and I'm unsure as to their measurements w/r/t the Aczel quote above. So I was hoping for some input - is either of these amps regarded as being particularly unreliable or particularly high quality? Or, from another angle, if you had my needs (1 RCA input, stereo output, no other features needed or desired, really, and has to satisfactorily drive Mission Audio speakers from about 15 years ago - I could grab the specifications later if necessary, but am not near them now), what would you purchase?

http://www.amazon.com/dp/B00026BQJ6/ref=as...two=&hvqmt=

http://www.amazon.com/Pyle-PAMP1000-Channe...power+amplifier

Incidentally, the reason I need this amp is the current receiver I am using is ugly, and somewhat noisy - it's a bottom-of-the-line mass-market unit from about 15 years ago, so I won't be sad to see it go.
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mzil
post Jun 23 2012, 01:24
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I take it you want a stereo volume control knob, right? Instead of "amp", usually short for "power amp(lifier)", what you really want is a bare bones (one input, no tone controls) integrated amp. At least that's the more common terminology in the US. It integrates a preamp (at the very least a volume knob, maybe balance too) with an amp, into one chassis. Is that correct?

[edit to add: If you get a straight power amp, no knobs, would it bug you that the only volume knob you have on your current control device may need to be re-calibrated everytime you switch from headphones to the out board amp?]

The thing is, stereo receivers (adds a tuner) outnumber integrated amps in a huge way (less so in Europe, but there too), yet they don't really cost more. You might consider an introductory receiver from Sherwood, Sony, Yamaha, or Denon simply because you'll have a larger choice of options and more vendors to choose from. Also buying "last year's closeouts" often can save you some money, or even used.

If what you don't like about your current receiver is a constant low level hiss, then these two amps from Amazon may be no better.[ I've never seen independent test reports that measure that for either of them, and I never trust manufacturer's specs.] Or when you say "noise" do you mean a symptom the current unit has developed over time? [Which could mean the volume knob simply needs a contact cleaning spray session]

This post has been edited by mzil: Jun 23 2012, 01:38
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tgadd0
post Jun 23 2012, 01:43
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QUOTE (mzil @ Jun 22 2012, 17:24) *
I take it you want a stereo volume control knob, right? ... Is that correct?

If what you don't like about your current receiver is a constant low level hiss, then these two amps from Amazon may be no better.[ I've never seen independent test reports that measure that for either of them, and I never trust manufacturer's specs.] Or when you say "noise" do you mean a symptom the current unit has developed over time? [Which could mean the volume knob simply needs a contact cleaning spray session]


I do not need a volume control knob, even. I suppose I'd be happy with a receiver that measures well, and has been independently verified, and I suppose I probably should have specifically asked if people had seen those for the models I linked. I have a volume control on my pre-amp (a relatively new Benchmark DAC1 HDR) and so do not need a pot on the stereo amp. I linked some cheap models because I'd rather not overpay, but I suppose I should say I have around $500 budget if some benefit could be gained (security in the knowledge that the amp has been measured as having sufficient stats would certainly be a benefit, to me). I don't currently use my tone controls, so don't anticipate needing them. I suppose I may want to EQ something at some point, though.

W/r/t the second question - there is and always has been constant low-level hiss on my receiver. Typically it is not noticeable as it's swallowed by the music, or by background noise of the city I live in, but in quiet passages and at unusually quiet times it can be a distraction. More recently the volume knob has started crackling when adjusted, but I so rarely adjust that I never bothered to Deoxit it. Fundamentally, I don't like the thing, and I'm not going to be happy with it even if I did clean it &etc for emotional reasons, as it were. blush.gif

Essentially, I'm looking for recommendations. Too many choices out there, too much snake oil sold, and all I want is something that measures well, isn't too ugly (bare-bones functional is fine, but looking at some of the Behringer stuff for example, the wife would never go for it), and isn't too terribly expensive.

ETA - no, Mzil, it would not bother me.

This post has been edited by tgadd0: Jun 23 2012, 01:44
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mzil
post Jun 23 2012, 02:01
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If, like me, you need to see independent reviews by outfits that have measured the noise floor as being low, the least expensive option I know of is the Behringer A500, which The Audio Critic think well of. What they didn't notice, however, which there are some YouTube videos which discuss the matter, is a problem that unit has where the distortion skyrockets (for some weird reason) if the volume knobs are placed at an attenuated level instead of full up, normal (but you wouldn't need to do that).

I can offer more help if you need links.

As for the "looks", I guess that's between you and the wife.

[Maybe hide it under a desk or in a closet? Other than the power switch, its not like you need access to it in use.]

This post has been edited by mzil: Jun 23 2012, 02:03
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tgadd0
post Jun 23 2012, 02:12
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Ha, thanks. I have suspected that I may just need to either bite the bullet and order something inexpensive and, well, gamble. Or, buy something like the Beringer. You mentioned that the Behringer was the least expensive option - do you know of others that are comparable price to the Behringer (i.e., let's say, no more than double the Behringer's price) that look cleaner, less plastic?

I had looked at the Parasound Zamp, which The Audio Critic also likes.
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mzil
post Jun 23 2012, 02:48
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Remember what I said about "Maybe you should consider a receiver and ignore the tuner part, only because there will be so many more options to choose from and there's more competition from vendors fighting to get your money, so the prices aren't really any higher"?

Well forget the word "receiver" and replace that with "A/V receiver"!

Hometheater.com measured the introductory Yamaha's line level input and it faired quite well, with impressively low noise:

"This graph shows that the RX-V371's left channel, from Audio1 input to speaker output with two channels driving 8-ohm loads, reaches 0.1% distortion at 81.9 watts and 1% distortion at 95.3 watts. Into 4 ohms, the amplifier reaches 0.1% distortion at 100.6 watts and 1% distortion at 121.1 watts.

There was no analog multichannel input to measure. THD+N from the Audio1 input to the speaker output was less than 0.010% at 1 kHz when driving 2.83 volts into an 8-ohm load. Crosstalk at 1 kHz driving 2.83 volts into an 8-ohm load was –76.34 dB left to right and –75.63 dB right to left. The signal-to-noise ratio with an 8-ohm load from 10 Hz to 24 kHz with "A" weighting was –107.30 dBrA.
—MJP" [emphasis mine]

[There's no such thing as "dBrA", by the way. They mean dBA or perhaps dB-A. They are misreading a display/read out their Audio Precision test machine has which reads:"dB r A" and they are errantly squishing it all together, but it is improper to include the "r" when printed as an abbreviation. Its a minor error, like writing, "I live in the USofA". How you (might) say it and how you print it are different things. You might say "dB regarding A weighting", or abbreviate it it "dBA", but not "dBrA".]

Although possibly discontinued, it is still around. and quite inexpensive.

This post has been edited by mzil: Jun 23 2012, 03:24
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Apesbrain
post Jun 23 2012, 13:44
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It would appear both amps you linked in your OP are the same unit with different branding. At least one other company sells that same amp on Amazon but with different knobs for $10 more:

http://www.amazon.com/Russound-X75-2-Chann..._cmu_pg__header

Note what the reviewers say about plugging your primary listening source into "Input 2". For $90 how can you go wrong? Anyway, if you don't like it, you can send it back -- it's Amazon.
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Arnold B. Kruege...
post Jun 24 2012, 23:09
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QUOTE (Apesbrain @ Jun 23 2012, 08:44) *
It would appear both amps you linked in your OP are the same unit with different branding. At least one other company sells that same amp on Amazon but with different knobs for $10 more:

http://www.amazon.com/Russound-X75-2-Chann..._cmu_pg__header

Note what the reviewers say about plugging your primary listening source into "Input 2". For $90 how can you go wrong? Anyway, if you don't like it, you can send it back -- it's Amazon.


The former point about receivers is supported by a product that appears to be very similar, but includes a FM tuner and a remote control for about the same price:

Cheap 100 wpc receiver with remote and line level outputs

It also has separate line level outputs for using an external power amp.

More details and user manual download
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