Review: Audiosource Inc. AMP 100 Amplifier

Category: Amplifiers

I'll never forget the sound of that Belles tube amp. Everything was so downright seductively natural. But how was I to come close let alone equal to that great "tube" sound at a price point one tenth of the famed Belles's one???

John offered me the Parasound HCA-800 Series II and made me a customer for life! That was way back in 1992. Thank you, John Rutan of Verona Audio Connection fame!!

Unfortunately...due to financial circumstances that followed about five years later...I had to let go of my treasure and the Parasound was no more. Over the years I never forgot that sound and remembered marvelling at how things had changed and what a remarkable achievement it was for the likes of companies such as Adcom, AudioSource and Parasound to be making these first-rate amps at such low prices.

Now recently I decided to dip into the pleasures of owning such great amplification again and wondered where it would lead and how that is . For I have very little of the popular stuff! In late December I embarked upon my new assignment and the journey began.

I don't care for modern receivers. They are massed produced glitter bugs that attract over-inflated ratings and embrace harsh constricted audio that no matter how many times are multiplied 5.1, 6.1 or more still equal bad sound. Surrounding one's self with this inferiority does not resolve the situation nor does it improve the already bad sonic performance. In fact...truth be only serves to worsen it.

The situation has become so bad that I just refuse to give these modern marvels of mediocrity any consideration. I simply cannot in good conscience recommend a modern A/V receiver to anyone. Certainly the stereo receivers of the past easily and effortlessly surpass these dreaded drones.

That is not to say that there aren't still some great stereo amplifiers out there. There are but the high end has 'em and they come at no small cost to the lover of the hobby. Yes...indeed the sonic purity and power of a Belles or Creek or great tube amp of any make can be had by those of unlimited pocket change and one can either take out a second mortgage to own such a system or settle for a solid performer from the past in search of a new home.

If you are one of these very fortunate individuals and already own one of these gems or have enough cash in hand to buy out Disney five times over then read no further as I would only be wasting your precious time. However...if you are like myself and live from week to week wondering if food will continue to appear on your table but still have an insatiable thirst for sonic perfection at low cost...then by all on!

The Purchase

Along comes the Audiosource Amp 100 from Phoenix Gold International with no bells or whistles very compact and attractive looking with its flat matte black finish selling on the internet for a paltry $120-$130! It is a stereo class A/B power amplifier that offers the audio enthusiast and casual listener alike solid performance and versatility. Similar more powerful versions are available from the manufacturer...Amp 200 and Amp 300. Class A/B amps are notorious for their efficiency and low transient intermodulation distortion {TIM}.

All AudioSource amps arrive with a two-year limited warranty. The dealer offers a really worthwhile extended warranty for just under $12 through Square Trade. You must pay for this service through PayPal although the vendor accepts other forms of payment for the merchandise itself.

Audiosource's main USA office is located in Portland, Oregon and the authorized vendor that I purchased the unit from is located in the nearby state of Washington. The gentleman offered Fed-Ex Ground shipping with excellent up-to-the-minute tracking results. Although I live here on the East Coast...I knew precisely when my amp would arrive! Total cost to me of amp w/shipping=$121... Outstanding!

The Arrival

When lifting the amp out of the box I could not help but notice that although small and compact...the unit had quite a substantial feel to it and one immediately senses high quality and first-rate build. It is of slim design standing at just under three inches tall by sixteen and a half inches wide by nine and a quarter inches deep weighing in at just under ten pounds out of the well marked and packed white box. The two-year limited transferable warranty and five page owner's manual are neatly sealed in a protective clear plastic bag with the usual suffocation warning.

The left front panel sports the red "Audiosource" logo along with a main power up button and two speaker selector buttons marked "A" & "B". The opposite right side of the amp offers a "Balance" control with the typical detented center position while the nearby "Volume" control offers non-detented but well marked volume levels.

The rear panel features two pairs of stereo inputs, h.d. 5-way binding posts for "A" and "B" speakers, an "Auto On" switch, a "Bridged" selector, a 400 watt rated AC unswitched outlet and stereo line outs. The mains itself is an unusually rugged heavy gauge power cord and I believe Kimber Kable would be proud as they believe that a dedicated mains cable can make for an audible improvement over those that are not.

This is an arguable point amongst audiophiles but I believe that the superb sonic performance of the AudioSource may cause the non-believers to at least reconsider their position on the matter...just a little food for thought here...nothing more...nothing less.

The unit is rated at 50 watts rms per channel both channels driven into 8 ohms with no more than .02% total harmonic distortion. The 4 ohm rating is 60 watts per channel. The Amp 100 can be bridged and used as a single mono block and in this mode its power is then tripled for a total of 150 watts into an 8 ohm load! Does this mean that the Amp 100 has HCC {High Current Capability}? The power bandwidth is shown as 20Hz to 20KHz but one site...Dynaco reported a response of 5Hz to 65KHz.

Audiosource uses discrete output components and toroidal power supplies in all of their amps. This combination provides first-rate circuitry which the purists will undoubtedly love! Toroidal power supplies are generally considered superior to all other types of transformers as hum and extraneous noises are all but eliminated. Anybody involved with the science of sound knows that this is pretty well documented at this point in time. The A-weighted S/N ratio is an impressive 107db.

My poor man's reference system currently consists of a Yamaha R-500 stereo receiver which boasts 40 watts per channel and a superb phono preamp, an absolutely lovely sounding Pioneer PL-518 direct drive turntable with an Ortofon OM5E magnetic phono cartridge mounted in the well designed s-shaped tonearm, Shure M97xE in a PE 3048, A-T 3482 in a Technics SL-D30 and finally Polk R-30 cherry towers.

I substituted the Yammy with this Amp 100 along with a Pioneer TX-5500 II AM/FM stereo tuner and a Radio Shack Realistic 1200B DJ mixer. This inexpensive classic mixer is capable of three mic sources plus two turntables and two auxiliary sources. It is one of Radio Shack's quieter mixers along with being the only stereo mixer I know of that boasted a magnetic phono preamp frequency bandwidth of 10Hz to 30KHz!

The tuner and turntable are patched to the mixer which in turn is connected to the "1" inputs of the Amp 100 with h.d. OFC RCA patchcords {purchased from the darn dollar store...of all places!} while a Toshiba single tray DVD/CD-R player is hooked up to the "2" inputs. Obviously one can substitute a decent AM/FM control amplifier/preamp and I'm sure that the more modern Rega Planar 1 turntable that boasts the superb RB100 tonearm fitted with Ortofon OM5E would certainly offer equal or better performance than the PL-518.

Originally the Yamaha R-500 and Polk R-30's were terminated with Mirasonic 18 ga. pure OFC wire and gold-plated banana plugs however this wire had become somewhat abused and chewed up by our newest family member and a new proper cable was in order. Although Mirasonic's zipcord was the most bang for the buck in its day, the company has since passed away making the cable no longer available and besides...with great advancement made recently in low cost professional high end installer cables...this seems to be the best way to go when installing the likes of an Amp 100...especially if long runs are involved for zoning purposes.

Help Once Again From Mr. Rutan's Audio Connection

Enter John Rutan of Verona, New Jersey's Audio Connection {} and staff member Mary along with Kimber Kable Kwik-12. John had proven to me in one of those memorable auditions years ago how certain high end cables could indeed make an audible improvement over your local hardware store's zipcord. There was also no doubt that Kimber Kable's 4PR generally outperformed Monster Cable and most other high-felootin' cable ripoffs.

But the 4PR was super thick, bulky, brittle and braidy looking with increasing cost. However...Mary was quick to point out that Kimber's new Kwik-12 {a separate report forthcoming} is "quickly" becoming increasingly popular amongst professional installers because of its reasonable price of $1.25 per foot and its off-white outer cover which blends superbly into most baseboards and decor.

I only needed fifteen feet total as my listening room is rather small and six or seven feet per run from amp to each speaker was more than enough. She said she would cut me a sixteen foot length and charge me only a buck a foot. She even gave me a little bit more for good measure {yes...a pun is intended} bringing the total to $16 with sales tax. Now that is a bargain!

However...the real bargain and treat was experienced after installing the first-rate wire with gold-plated banana plugs {although John feels that silver-plated ones are better} to the back of the Amp 100 with the yellow and white bare ends connected to the five-way binding posts of the R-30 loudspeakers. This situation was reversed when using the Yamaha R-500 receiver because the Yammy sports spring-loaded terminals whereas the AudioSource uses five-way posts perfect for my banana plugs. I just don't have the extra cash at the moment for buying another pair of ten dollar plugs but perhaps sometime in the future this will happen...then again...maybe not!

OK But How Does It Sound?

I only state this because the sound of my little reference system is now so good as I really don't want to tamper with it. Then again...I do like to tinker a bit. OK...I admit it...I did switch back for a moment and there is no comparison to my surprise and delight! The AudioSource Amp 100 has heaps more detail and clarity and this is not easy for me to admit as I consider the Yamaha Natural Sound Receivers of the past to be among the very best integrated amplifiers. My records and cd's now sound more open detailed and airy than I ever thought least within my financial means.

Loggins & Messina's "Be Free" off their "Greatest Hits" album along with Art Garfunkel's "I Shall Sing", "Mary Was An Only Child" and "Woyaya" from "Angel Clare" represent excellent tracks from their respective Columbia albums on vinyl. Tin Tin's "Astral Taxi" on Atco vinyl proves to me beyond the shadow of a doubt that vinyl still reigns supreme with the Amp 100 allowing the Ortofon OM5E to do its thing and really shine with the utmost detail and neutrality. Plus these aren't even audiophile special pressings!

This three dimensional purity was first experienced immediately after turning the amp on but after an hour or so I could hear the new amp and Kimber Kable burning in so to speak! Another words...the sound got deeper and more well defined as the break in period progressed.

Equally impressive is the extremely well balanced output of the stereo channels from left to right especially with a phono source. This allows the Ortofon OM5E to present a pinpoint well focused but wide stereo image with the wonderful "Balance" control dead centered that I have yet to hear through a stereo receiver or integrated amp from any generation with the original AR Amplifier being a possible exception with its "Null" circuit. Usually one channel is slightly favored over the other in either output or tone.

Now, keep in mind that I generally like to use the two-o'clock position on my tone controls but find lately that I have become less dependent on them as none exist with my present setup. And just when I thought I'd switch back to the Yammy which does have bass and treble controls...well...I just couldn't bring myself to do so as I just don't want to risk losing the sonic purity and perfection I'm hearing for the first time with the AudioSource!

Another thing that should be stated here is that I am absolutely awestruck by the quiet and low volume dynamic performance of the combo. Increasing the volume setting to the max seems to introduce no hum or hiss at all while the amp itself appears not to "clip" at all! Whatever clipping was reached was certainly softened by this amp's top-notch build and circuitry. Again...I must emphasize the fact that there is absolutely no tonal compensation of any genre used here.

Jethro Tull's "Aqualung" album on vinyl features the one-legged flutist...Ian Anderson {he stands on one leg while performing} and I could swear that I could actually feel the wind flowing through his instrument for the very first time! The bass is outstanding as are the mids and highs are clear but not a tad too sweet like on the Parasound amps. Just listen to Vangelis's "Heaven And Hell" Side 2 Track 2 and you will experience spine-tingling rapid-fire high-speed transients of the bells!

WBGO...Jazz 88.3 FM sounds awesome! Basses go really deep and defined while percussion especially cymbals sound so clear and not smeared. The sound is full with good neutral and never fatiguing.

The sound builds and then quickly decays defining overtones with remarkable clarity. The soundstage before you now expands and opens up with a three-dimensional purity that only a high end system can provide. My favorite test record is the "Professor Johnson" one and Side One clearly demonstrates first rate transients and accuracy of musical timbre through my little reference system with my new found love in control!

This is not my first experience with an Audiosource amplifier nor is it my first encounter with three-dimensional purity. No...I have John Rutan to thank for that! The Amp 100/Polk R-30 combo is very reminiscent of B&W speakers he had paired to a nice Rotel amplifier some time ago. What is truly incredible is that the sound is even somewhat reminiscent of the Belles tube amp/Vandersteen 1B or 2Ce combo he let me experience as far back as 1992! The Amp 100 itself is also comparable to its predecessor...Amp One. I'll never forget how well that model sounded hitched to a pair of Allison Six cubes at the local highway electronics market back in '92.

Incidentally...although the amp is extremely quiet in can hear it switch in and out or back and forth from line one and two if your component on line one is quiet for about three seconds or more time. This is a double-edged sword that can become an annoyance especially if you have a turntable as I do hooked up to line one. The amplifier has a built in priority override sensor under these circumstances. This means that if your album gets quiet even briefly on line one... "1" ...then the amp will somewhat quickly switch to line two if it is active or until a signal is sensed back on line one. When a signal is present on line one it immediately overrides whatever is active on line two.

The easiest way to avoid this nuisance is not to hook up the "1" inputs at all and to just use line two or the "2" inputs on the back of the unit. Then...all of that signal-sensing nonsense ceases and desists. On the other advice is to experiment a bit with this feature as I have.

Just so you know...I have become accustomed to the signal sensing thing of line one and have left my turntable and tuner connected to the mixer on that line. It's kind of neat in a way as it mutes my turntable while the Ortofon OM5E slowly descends and touches the lead-in groove of my vinyl. There are no "whoomph!" sounds.

Keep in mind that the signal-sensing of the inputs is not to be confused with the signal sensing that can be used to turn the amp on regardless of what set of inputs one chooses to use. The Amp 100 can be set via a tiny slider control on the rear panel to turn on and off automatically. By selecting the "Auto ON" setting with the front power button remaining can have the amp power up and shut off all by its lonesome! If no signal is present on either line for roughly ten minutes or more...the green light on the "power" button changes back to red.

Under this circumstance...the amp goes into some sort of standby mode with the power button on the front panel lit red and then when a signal is supplied to the amp again it changes to a fairly bright green indicating that the amp is now in operation. Of course one can choose to power up manually by setting the rear selector appropriately and just depressing the front power button. To each...his or her own!

When hooking up one pair of speakers to the amp's "A" simply depresses the "A" speaker selector button which then in turn lights up red. When depressing the "B" selector button, it also lights up red. Depressing either button individually causes the other one to stay out. Depressing both simultaneously activates both sets of loudspeakers and both the "A" and "B" buttons are lit together. When two pairs of loudspeakers are used {"A" & "B"}...their minimum impedence should be 8 ohms. The amp is not designed to handle 2 ohm loads.

However...if you are extremely fortunate to have in your posession two pairs of retro Dynaco A-25's...then these very stable 8 ohm classics will pose no threat to the Amp 100. Similar classic Smaller Advents on the other hand are not 8 ohm rated but are 4 ohm transducers and more than one pair cannot be used with this amp.


Even though the Amp 100 is first rate as a stereo only amplifier with the R-30's I can easily see where this amp is extremely versatile. If I ever decide to trade in the efficient Polks for the extremely less efficient entry level Maggies {don't worry it ain't gonna happen any time soon as the Polks are so-ooo-ooo good!}...I can easily and economically do so simply by purchasing another Amp 100 and setting the tiny rear slider of both to the "Bridged" mode for a walloping 180 watts of rms power per channel into 4 ohms as that is exactly the impedence the Maggies are rated at! The Amp 100 triples its output when bridged.

The Owner's Manual demonstrates how to phase each speaker when doing so. Speaking of which...this manual is not as clear and detailed as I would have liked. I really need a magnifying glass to read it cleanly. Enough info is provided for the basics but there will clearly be situations that require some users to call the company's "Tech HotLine". When you'll find that the technician is very knowledgable and here is where Audiosource's support is truly tops.

Currently...if one enters their website at one can find a tab for support and download Adobe Acrobat Reader manuals except for one problem...when you attempt to do receive a message from I.E. stating that the page is still under construction. Hmmmmmm!

The amp itself can be used in many other ways. It can be used as a remote Zone Two or Zone Three amplifier when used in combination with one of the newer "Zone" receivers. The outputs on these receivers can effectively control and activate the Amp 100 regardless of what zone or listening room it is to be used in...let's say...a bedroom for example. Ha-haa! Better have some Barry White on hand!

The fixed line outputs of the Amp 100 can in turn feed the signal to yet another zone amp or device such as a subwoofer. The Amp 100 can be used with another Amp 100 for bi-amping purposes where the woofer and tweeter of a given speaker model need to be controlled separately for best results such as the old Advent AS2 tower I reviewed years ago.

What really separates the Amp 100 from most other quality power amplifiers is the fact that it is entirely possible for one to forgo the expense of a separate control amp/preamp by simply utilizing the two sets of inputs for say...a properly interconnected IPOD, CD/DVD player, tuner or preamped turntable. I state this here because many power amps require that their hidden or front level controls to be set accordingly to one's selected preamplifier.

The line inputs of the Amp 100 for the most part can easily handle the fixed outputs of said devices without fear of overload distortion. There are a few exceptions such as if you use the "Normalize" feature during the burning process of your CD's as I did on a few. Under this circumstance...the Amp 100 will in no small way mask or soften the over modulation distortion at all! probably is best to use a player with a variable output control.

The extremely smooth front volume and balance controls work well here indeed also. If more than two sources are used, one can simply opt for an inexpensive auxiliary selector box available from many electronic supply houses such as Radio Shack.

The auto power on and signal sensing of the Amp 100 is very reminiscent of those found on many powered subwoofers. Audiosource makes numerous amplifiers for many companies and my bet is that if your sub is self-powered...then Audiosource probably built the amp for it. This enables the company to use their expertise in marketing low cost high performing amplifiers without the proverbial "middle man". The company literally manufactures thousands upon thousands of these amps in their Taiwan plant. Little advertising and word of mouth reports from owners also help keep prices much lower than you'd expect.

In Conclusion

I have had this little cool-running giant killer in my possession now for 5 months. It has been utterly reliable and opened up to the point that no further burn in can take place except for when I hookup my new TCC TC-160LC MM/MC Phono Preamp soon as it arrives. .I just feel confident that this is a robust amp that will render many years of service to myself and others that are fortunate enough to so choose it.

If there truly is a beauty in simplicity...then the AudioSource Amp 100 is that school of thought's most primal example. The uncluttered front panel easily gets the poor man's gold medal in this writer's humbled opinion and the smooth but surefire "feel" of the controls is most welcome and makes for a comfortable feel.

The amplifier easily and effortlessly meets its rms power rating of fifty watts per channel into 8 ohms but yet never seems to sound blaringly loud or piercing. Please be aware of the fact that if your loudspeakers are of low efficiency and you insist on unusually high listening levels...then you should consider a more powerful amp. Still...remember that when the amplifier is bridged it triples its output! Two of these little guys as mono blocks still render a most economical bang for the buck.

Yet it has all the speed and more one could possibly expect for its asking price. In the discussion of solid state vs. is a classic example of how a well made solid state unit can compare very favorably to a good tube type. How did AudioSource accomplish all that clean power in this low cost unit?

I'm even starting to listen to my cd's again. Don't let that cat out of the bag...oops...I just did. I also like the fact that anyone in our household can listen to any of the sources by simply operating them without a selector switch. Even if its power spec doesn't quite grab you...its sheer musicality undoubtedly will. For those of you getting your feet wet for the first time in Analog/Vinyl and High End Audio on the strictest of budgets...oh yeah...this one's a real "no-brainer" for sure!

Nonetheless...the AudioSource Amp 100 is simply one of those rare bargains {remember the old Dynaco A-25's???} that only surface every fifteen or twenty years in this business. At its price point and performance truly and sincerely has no peer. The Bottom Line...
I know of no other modern audio component amplifier that can touch Audiosource's Amp 100 at its price. It is the proverbial "steal" in the most sincere and truest sense of the doggone forsaken word!

...PJS Series 2

Associated gear
Pioneer PL-518 Turntable
Polk R-30 Cherry Speakers
RS 1200 Preamp/Mixer
Pioneer TX-5500 II Tuner
Shure M97xE
A-T "Red Ed"
Ortofon OM5E
A-T 3482

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