In today’s day and age of convenience over quality, traditional separates are becoming less and less in demand. In fact, many stereo systems today are powered by low-powered, low quality multi-channel receivers that promise big wattage numbers in a small package. At least two of the three Integrated amplifiers in this comparison all tip the scales at over 30lbs and would cost thousands if new today. The parts quality of these units is superior to much of what is available today, especially under $1500, from the Black gate Audio-Grade capacitors used in the Yamaha AX-900U to the Nichicon Muse and Elna Silmics used in the Sony TA-F707ES. These three units offer exceptional value in sound quality and reliability in today’s used audio equipment market. Now, the question is which would should you choose?
Denon PMA-920 Integrated Amplifier
Coming in at around $250 the Denon is the lowest price of the bunch versus $400 for the Yamaha and $500 for the Sony. When inspecting the inside of the unit it is apparent that the Denon does not approach the other two in build/ parts quality. Of course, a high degree of build quality/ parts quality does not always equal excellent sound.
I first set the Denon up with my power hungry Kef 104/2’s in my 15’X20′ listening room. I started with a demanding drum solo track and noted the decent bass drum impact, neutral midrange, and non-agressive but slightly grainy highs. The Denon did a decent job of imaging but was not able to bring that last bit of realism to the recording that gives me the butterflies. Cymbals did not have the air and space of the best amplifiers. As I turned up the volume and tried different music, I could tell that the Denon began to have trouble keeping up and as the sound started to become out of sync with the highs becoming harsher and bass becoming looser, I decided to try some different speakers, the Technics SB-7000. The SB-7000’s offer a much easier load on most amplifiers in comparison to the low impedance dipping Kef’s. I immediately noticed a difference when playing the same track. The difference I noticed in sound was not due to the change in speakers as I know their sound signature, having tried many different amps and spending many hours listening to the Technics. The difference was most noticed when playing classical recordings with large dynamic swings and also on live recordings with immediate impact. The Denon went from sounding strained in the highs and lacking in bass accuracy with the Kefs to being respectable in all categories with the Technics. The Denon did not approach the best in imaging and soundstage presence. It was as if their was a small veil in front of the speakers restricting that last bit of detail that makes the right recordings sound alive.
After spending a fair amount of time with the Denon and coming to the same general conclusion as previously stated I decided to move on to the Sony TA-F707ES.Power Output: 115 Watts Per Channel/ 8 Ohms
Frequency Response: 20Hz-20kHz +/- 1.5dB
Signal to Noise Ratio: 75dB (MC), 94dB (MM), 107dB (Line)
Made from 1988-1991
Made in Japan
Sony TA-F707ES Integrated Amplifier
The Sony TA-F707ES is the best built amp of the group, it is also the most expensive, $1200 Retail, and $500-$700 used. After reading many positive things about the Sony I had high hopes for it. With a rated 100 Watts/8 Ohms, the Sony has the least rated power of the group, but is also the heaviest at a whopping 46lbs.
Just as with the Denon, I first set up the Sony with the Kef 104/2’s in my 15’X20′ listening room. I started with my trusty drum solo track and was grinning immediately. The TA-F707ES exhibited excellent detail, dynamics, and a full sounding midrange that gave life to the music. Imaging was very good if not the best I have heard. Overall tonal balance was a smooth, airy, and clean. If I had to complain about one thing I would say that bass reproduction was not as good as I had hoped for. The Sony did a fairly convincing job in speed and timing, but the visceral impact, specifically with bass drums was not as convincing as I have heard with say, a Krell KSA series. Still, the Sony was much better across the entire spectrum in comparison to the Denon and for the price a true bargain.Power Output: 100 Watts/ 8 Ohms
Frequency Response: 2Hz-200kHz
Yamaha AX-900U Integrated Amplifier
Last to listen to was the Yamaha. After listening to the Sony for a few days, I didn’t think I would be getting any better. Sure, the Sony lacked that last bit of bass accuracy but it was so good in other areas that I had all but forgot about what I was missing. I replaced the Sony with the Yamaha and started with my trusty drum solo track. Wow! The Yamaha instantly filled the bottom end that had been missing and with authority. Although the two amps were rated around the same power, the Yamaha seemed to fill the room with excellent sound more effortlessly. I could crank the volume to stupid levels without strain or fatigue. The sound from top to bottom was well balanced with the Yamaha, clearer and more lifelike than the Sony in all areas other than the highest highs such as the upper most octave of brass and cymbals. With every track I played I smiled when playing the Yamaha. I found myself enjoying the music more-so than with the other two amps. Vocals were the most realistic with the Yamaha, with the minute details of recordings coming to life. Imaging and soundstage presentation were a degree above the Sony and several above the Denon. I think we have a winner!
Power Output: 130 Watts Per Channel/ 8 Ohms
Frequency Response: 20Hz-50kHz +/- .5dB
Total Harmonic Distortion: 0.005%
After Listening to all three units individually and back to back for an extended amount of time with different speakers, I can recommend two and say that money can be spent elsewhere for better results on one. The Sony was impressive. If the Yamaha had not been in the picture I would have been happy with it. On most speakers the Sony was an excellent sounding unit overall; however, on hard to drive speakers the Sony had a tendency to lose steam long before the Yamaha, especially in bass. Next we have the Denon. I cannot recommend the PMA-920 at its current going rate. Their are several better sounding units in its price range including most of the NAD PE series units, the Nakamichi TA and SR series Receivers, and the Luxman R-115. The Denon’s overall sound was on the dark side, lacking detail of the others, and unable to handle difficult loads or handle high level dynamics. The clear overall winner was the Yamaha. I can wholeheartedly recommend it for someone looking for amplification in its price range of $300-$600. The Yamaha AX-900U is a true powerhouse with a sound that is very close to the same league as the big buck separates from Levinson, Krell, and others.