Digital Drive: REVIEW: Onkyo DX-7555 CD Player/Recorder by machani

Model:	DX-7555
Category:	CD Player/Recorder
Suggested Retail Price:	$699
Description:	Audiophile grade CD player
Manufacturer URL:	Onkyo
Model Picture:	View

Review by machani on February 05, 2008 at 01:39:18
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for the DX-7555

Background:
I was looking for a mid priced single-disk CD player to replace my aging Marantz CC4300 CD changer as the main digital source in my system. I once praised the sonics of the Marantz as being "silky smooth and the bass is deep and controlled. It is also both sensitive and dynamic".

Three years later, with many system upgrades including better speakers and much more revealing cables, the shortcomings of the Marantz shows. Its main drawback is the treble glare that makes some kinds of music(especially brass bands and classical music) not very pleasant to listen to. It's mid bass is not as articulate and authoritative as I would have liked, giving a sort of weak presentation.

After considering a number of players, including the Marantz CD5001 and Cambridge Audio Azur 640C (v2), I chose the Onkyo DX7555 due to its positive reviews and excellent specifications, including the Wolfson WM9740 24-bit/192 kHz DAC (that is also found in the Cambridge Audio Azur 640C (v2)), its anti-resonant chassis and its low-jitter clock circuit (said to be accurate to +/- 1.5ppm).

BHPhotoVideo.com has the Onkyo on sale for $479.95, not bad for what The Absolute Sound says "in the two-channel realm, it held its own against the Lexicon RT-20, a $5000 multichannel universal-disc player."

Looks wise it resembles the Cambridge Audio Azur 640c in its simplicity, while maintaining the classic 1980's Onkyo styling.

Initial Listening Impressions:
Cutting to the chase on its sound, my first impression was that it sounded more detailed and conveyed more venue information than the Marantz. The mid bass was more authoritative, faster and less bloated than the Marantz. It also producted more natural timbres with strings, horns and percussion. I then spent hours flipping through all my favourite CDs. It was that good.

I did notice, though, that it sounded little rolled off on the top, somewhat congested in the mids (lacking smoothness) and the background not black as I expected. However, I attributed this to fact that this was a brand new player and then decided to go through the roller coaster ride of the break in period - before doing any serious evaluation.

Things began to settle after about 15 to 20 hours playing time, where the congestion began to smooth out and clarity began to improve. After about 30 hours I could hear very few further incremental changes. But I let it play for a few more days before performing the AB comparisons with my Marantz, with both players connected to my Tube Audio Design TAD150 preamp with Audioquest Jaguar ICs.

Extended Audioning Impressions:
Compared with the Marantz, the Onkyo's soundstage was wider and deeper, with more precise and believable imaging. The imaging and channel balance are so precise and spot on that I had to reposition my speakers, using very precise measurements to the tune of a mere inch here and an inch there, so that the central image was aligned with the sweetspot. The hall and venue information the Onkyo conveys within the soundstage makes it sound pretty life-like. Overall the Onkyo's presentation is natural, linear and non-fatiguing.

My pleasure was short lived. Something began to bother me after a while.

Yes, the Onkyo sounded neutral, detailed and non-fatiguing. But it also sounded a clinical and uninvolving. Flipping back and forth between the two players I began to better understand the differences.

While the Onkyo sounded very neutral, the Marantz sounded more Organic, despite being an inferior player. The treble in the Onkyo was a tad soft and its mid-range was also slightly less palpable. I found vocals, high hat, piano and brush sounds to be less involving and somewhat artificial and veiled. So much that, compared to the Marantz, certain kinds of music, for example, Mark Knopfler's guitar in "Brothers in Arms" or Shirley Horns vocals in the track "Once I Loved", lost their emotional impact.

I played with the DAC filter settings, which has a "Sharp" mode which keeps the frequency curve flat to 20kHz or "Slow" which has a gradual roll off after 15kHz. Even with with the filter seat at "Sharp", the treble was still too soft.

The Anticlimax:
The sound of the treble was almost as if I was using cheap interconnects. But I was using Audioquest Jaguars (with 36v DBS) which is capable of revealing far more exciting treble. Then I remember saying to myself "the engineers at Marantz are also audiophiles, and the engineers at Onkyo are, well, engineers".

Being disappointed, I was getting ready to sell the Onkyo and dreaded the thought of having to get another CD Player and go through the roller coaster ride again (mainly from a lack of time).

I tried using the Dakion R203 feedback stabilizer that I had on the Marantz on the Onkyo. But the Dakiom seemed to have absolutely no impact, except somewhat reduce the venue sounds and compress the soundstage. (I later realized that the analog output stage on the Onkyo probably did not utilize negative feedback in its design, which is thus not suitable for using a Dakiom device).

The Solution:
Then, a thought struck me. I remember that years ago I replaced the stock power cord on my Marantz with a DIY one using Belden 89802 shielded twisted pair cable. I remember it improved the treble and detail.

Now the stock power cord on the Onkyo is not detachable, but upon removing the chassis cover and looking under the hood I was pleasantly surprised to find that the cord can be easily unplugged from the power supply board. (A slight press on the release tab of the female plug is enough). Furthermore, the two male pins on the power supply board are just the right size and distance apart for using a power cord with a C7 adapter. (Some of the plastic on the C7 connecter needs to be shaved off. It is NOT advisable to force the connector in).

I had a used AudioQuest NRG 1.5 available and was able to install the new cable very easily, taking care to use wire straps to hold the heavier AudioQuest cable securely along the inner wall of the chassis, and also marking the cable on both ends to maintain the original polarity of the stock power cable.

With the new AQ NRG 1.5 power cord securely in place. I began to repeat my audition of the Onkyo.

I remember feeling that "wow" factor once again!

The treble, overall clarity and transparency improved. The midrange became definitely clearer and the veil disappeared. The sound became actually quite involving. The top end was not rolled off, and tonality improved. The bass became more tuneful and articulate. The noise floor has lowered and some tracks sounded less muddled and more coherent. Vocals, high hat, piano and brush sounds are much clearer and more real.

This time Mark Knopfler's guitar and Shirly Horns vocals had the huge emotional impact that they should have.

Overall, this was entirely new experience!

Just to be sure I was not succombing to the dreaded "placebo effect" I repeated my ABX testing after a day, only to re-confirm that the stock power cord was indeed the culprit! It is the Achilles heel if you will, of the Onkyo DX7555.

So much that I would imagine any decent power cord that is shielded against EMI/RFI (or one employs a noise-cancelling design like the star-quad, solid-core, Audioquest NRG 1.5) would improve the sonics over the stock cord, which is just a pair of insulated 18awg wire running in parallel.

Playing with the DAC filter setting again, I found that I could actually enjoy some music tracks better with the Filter set at "Slow". (It tends to give a more relaxed presentation with good imaging).

A better power cord elevates this cable to another league altogether, and now I definitely am NOT planning to sell the Onkyo!

Conclusion:
This is an outstanding, audiophile grade CD player with extremely low-jitter performance. It's Achille's heel is the stock power cord which MUST be replaced.
_
C N Machani

Product Weakness:	Sounds un-involving and slightly veiled with the stock power cord. Need to open the hood to replace the stock power cord.
Product Strengths:	Transparency, excellent specs, ultra-low jitter, detail, linear response, realistic soundstage with precise imaging, non-fatiguing, authoritative controlled bass.

Associated Equipment for this Review:

Amplifier: Cayin TA-30
Preamplifier (or None if Integrated): Tube Audio Design TAD-150
Sources (CDP/Turntable): Onkyo DX-7555
Speakers: Quad 22L
Cables/Interconnects: AudioQuest Jaguar (36v DBS), AudioQuest CV-4 (48v DBS) speaker cables, AudioQuest NRG-1.5 and NRG-2 power cord
Music Used (Genre/Selections): Acoustic rock, jazz, classical. FIM Audiophile Reference CD
Room Size (LxWxH): 18 x 14 x 9
Room Comments/Treatments: Speaker placement
Time Period/Length of Audition: Two weeks
Other (Power Conditioner etc.): Furman PST-8D
Type of Audition/Review: Home Audition

Amplifier:	Cayin TA-30
Preamplifier (or None if Integrated):	Tube Audio Design TAD-150
Sources (CDP/Turntable):	Onkyo DX-7555
Speakers:	Quad 22L
Cables/Interconnects:	AudioQuest Jaguar (36v DBS), AudioQuest CV-4 (48v DBS) speaker cables, AudioQuest NRG-1.5 and NRG-2 power cord
Music Used (Genre/Selections):	Acoustic rock, jazz, classical. FIM Audiophile Reference CD
Room Size (LxWxH):	18 x 14 x 9
Room Comments/Treatments:	Speaker placement
Time Period/Length of Audition:	Two weeks
Other (Power Conditioner etc.):	Furman PST-8D
Type of Audition/Review:	Home Audition