I was contemplating getting a decent sounding, yet not very expensive headphone amplifier to drive my Sennheiser HD580’s. My dilemma was that neither my source nor my amplification offered me any sockets for headphones. I was using a hand built headphone amplifier put together by a good friend but I was of the opinion that I needed something more powerful and more refined. After doing a bit of research as to what mates well with the Sennheiser and be better than what I have at present, I finally came to a conclusion that there is nothing out there that would really do justice at under $400. I short listed few headphone amps costing between $400-500 and was about to go ahead with my purchase when I came across a Denon PMA-S10 Integrated amplifier for sale. During my initial checking on the web I was surprised that there was hardly any information available on this amplifier, except for the fact that it is prominently listed on the Denon’s Japanese website. The only information available was the list price (J. Yen 220,000 which calculates to be $2,200 at the prevailing exchange rate back in 1995) and basic power output which is stated at 50 watts/ch into8 Ohms and 100 watts/ch into 4 Ohms! There are not many integrated amplifiers out there which actually double in output power as the resistance is halved at the speaker end. High end manufacturers claim such specs and those are Jeff Rowland, Krell, Mark Levinson and some others. Nonetheless, specs are only guidelines and they cannot possibly give any indication of how an amp will actually sound like. It’s only during the listening/evaluation that you find out what the amp is really capable of. Let’s get on with the Denon PMA-S10, shall we? WHY AN INTEGRATED? There is of course certain advantage when it comes to Integrated amplifiers. Combining power and pre-amplifier means all the functions are put into a single chassis saving costs in terms of power supplies and doing away with one additional chassis. Hum is reduced because amplifier and pre-amplifier now share exactly the same ground voltage, so less shielding is required The need for an additional interconnect is also not there if it is a single chassis, the preamp output buffer and power amp input buffer is also done away with. An integrated amplifier allows the design engineer to design the pre-amplifier output circuit and power amplifier input circuit to be an almost perfect match since the characteristics of the interfaces are known. This is an established method of delivering high performance in a more convenient and cost-effective package. FEATURES AND FACILITIES: This amplifier was mainly sold in the Japanese domestic market and therefore is available in only 100 Volt version. Some of the other models from Denon in the ‘S’ series are also being sold in same way along with a transformer suitable for use with local electric supply and giving an output of 100 Volts. This amplifier tips the scales at just above 15 Kg’s! For a 50 watt amplifier this is a monster. Even the Krell KAV-300i with 150w/ch weighs less than this, an amplifier which I never liked. There is another model of Denon which is very popular with audiophiles, although I have not heard it but I am to understand it is a direct descendant of the high-end 'S' series of Denon amplifiers, notably the Denon PMA-2000 (in a few variants) which is an 80 watt/ch amplifier. These amps are still available and plenty of information can be found with a bit of search on the web. The front fascia, in champagne gold finish is typical of what a classic 70's and early 80's amp would look like. The quarter inch thick front panel, large volume control, and an equally large selector switch. There is a rec-out selector, tone defeat button (to disable the bass, treble and balance circuitry) and finally a power button (with a small yellow light to indicate the amp is switched on). The bottom of the amp is all shiny copper. The back side of the amp features very solid speaker terminals ( for a single pair of speakers) which are fully gold plated as well as all the inputs provided. Next to the phono socket, there is a black button which switches back and forth from MM to MC. Detachable three prong input power cable receptacle is provided to power the amplifier. Three flat pin output receptacles to feed other equipment if need be are also provided. MUSIC USED FOR EVALUATION: SACD Rimsky-Korsakov: Scheherazade; Stravinsky: Song of the Nightingale (RCA Living Stereo) Michel Camilo - Live at the Blue Note Eleanor McEvoy – Yola Sting – Sacred Love Santana – Abaraxes Shaft (Original Soundtrack) Casino Royale (Original Soundtrack) Roxy Music – Avalon CD Dave Grusin – Gershwin Connection Supertramp – Breakfast in America Patricia Barber – Cafe Blue Cassandra Wilson-New Moon Daughter Dominic Miller – Shapes Ella Fitzgerald and Louis Armstrong – Porgy and Bess Joni Mitchell – Clouds, Both Sides Now Keb Mo – Slow Down VINYL: Sonny Rollins – Cool Struttin’ Peter Gabriel – So ASSOCIATED EQUIPMENT: Sources: Rega Planar 3 with Ortofon, and A&R cartridges, Philips DVD 963SA SACD/DVD Player, Quad 67 CD Amplification: Quad 66/606II (140 w/ch) Cables: Canare Star Quad (effective 11AWG) bi-wire speaker cable, MIT, Monster and Cable Talk Interconnect cables. SPEAKERS USED FOR EVALUATION: Chartwell LS3/5a (15 Ohm Version) Rogers LS3/5a (11 Ohm Version) Energy XL-25 (8 Ohms) belonging to a friend Kef Reference 2 (4 Ohms)Main Speakers Rel Strata III HOW IT SOUNDED: The evaluation/comparison of the amplifier was done over a period of 4 weeks and critical listening was done each time only after the amplifier was in operation for at least 45 minutes. This amplifier is very sensitive when it comes to power supply since I did a test on 110 Volt supply and the sound from the amp was not anywhere near what it was capable of producing when proper power feed was given through the step down transformer giving 100 volt output to drive the amplifier. After acquiring the Denon, I shelved the idea of getting a headphone amplifier, since I found this amplifier so good for driving the Sennheiser, that buying a $400 headphone amplifier would really not be a big upgrade for me. They only possibility to get really good sound would be for me to spend in access of maybe $500-1000 to really better the Denon in every respect. The amplifier was capable of giving me a good ear massage driving the Sennheiser at just 10 o'clock position. The tone defeat button on the amplifier when checked through the headphones gave me an indication that the all the bells and whistles incorporated in terms of circuitry are of very high quality as the difference was hardly noticeable. Nonetheless, for the sake of record it should be noted that all the listening/evaluation was done with the the circuitry bypassed. Now that I realised how good the Denon was for driving the headphone I was really curious to find out what it would sound like when driving real world speaker load even though I did not get it for this reason. I did not test the amplifier with just 4 different type of speakers, but, all posing a very different type of load to the amp from 4 to 15 Ohms. Denon managed each speaker gracefully and did not give me even the slightest of impression that it was struggling at any stage even when pushed and called upon to deliver the dynamics demanded by any particular piece of music. Not many amps are capable of driving a variety of load, let alone sounding musical and at the same time having an effortless delivery. A remarkable feat indeed for an integrated amp since I have tested different speakers and found many amplifiers are good at driving either high impedance or low impedance loads. There are exceptions indeed, but, when we generally talk about exceptions it really means some high-end amplifiers costing several thousand $$$. Rimsky Karsakov's Scheherazade as most would know, is a pig to reproduce, this piece of war music can easily trip any unsuspecting amp and speaker combo when it approaches its climax, the Denon sailed through and maintained the integrity of the music pretty well. Listening to Eleanor McEvoy's album Yola (the first track), the amplifier gave me an indication of how good it is when it comes to the background noise, it was absolutely silent and only the music was being reproduced, there was no hint of any hiss or noise, this means the amp's noise floor is way below the audible range. I not only sensed it when using the speakers but also when listening to it through the Sennheiser. There was none of the very annoying upper midrange or lower treble grain, glare, or hardness that we often hear from typical Integrated amplifiers. COMPARISON WITH MY EXISTING AMPLIFIER: My main amplifier was the Quad 606II and Pre amplifier being the Quad 66, there is of course the difference in power rating, 140 watts/ch for the Quad versus 50 watts/ch for Denon. There was obvious difference when it came to driving the speakers authoritatively, the Quad was in a different league, nonetheless, the Denon gave me an impression that it was more like an 80 watt amp rather than the specified 50 watts/ch. The only difference between the two amps was the midrange, the Quad had a very liquid like midrange in comparison to the Denon, it had that uncanny ability to extract a bit more detail than what the Denon could. The voices had sort of an aura around them when it came to Quad and the Denon was sort of flat sounding. Nonetheless Denon is certainly not laid back, if I have to describe its reproduction of the entire audible range, it was more towards being flat rather than highlighting any particular frequency in the audible range. The sound stage on the Quad was much bigger, from back to front as well as from left to right when compared to the Denon. Listening to Keb Mo's album Slow Down and particularly the third track “Everything I need”, just when the word “everything” is being rendered, the bass was sort of circling around the two speakers like the Ring of Saturn circling around the planet, with Quad, the ring was larger and denser. I guess this also could be attributed to the difference in power output, but, it sure was the case when comparing the two. When comparing the Phono Stage I felt the Quad was superior. Denon was a bit thin sounding, unlike the Quad which if I dare say it, was lush sounding and had more authority. Again the midrange had the same characteristics as mentioned earlier. FINAL THOUGHTS: The Denon PMA-S10 is an amplifier with more than sufficient power for even difficult to drive speakers; it delivers clean, detailed, and neutral sound that integrates well with any speakers and at the same time it has an excellent build quality that makes for a very impressive product indeed. This is not an amp for those who are looking for an upfront and in the face music, but, this is an amplifier one can listen to for hours without experiencing ear fatigue. For the price that I paid for this amplifier, it would have been a stupid mistake on my part if I had let the opportunity pass-by, it was too good a deal at just $250! To be honest, this amplifier would be a worthwhile purchase even at around $600-800 provided one can come across one. I can’t recall having been as thoroughly impressed by an integrated amplifier in quite some time. At normal listening levels (between 10 and 11 o' clock) it was an extremely clean and clear performer with an uncanny ability to let the music flow from your speakers.