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Onkyo DX-7555 vs. HeadAmp GS-1 vs. Onkyo A-9555

post #1 of 32
Thread Starter 
There's been a lot of talk recently regarding the headphone outs on integrated amplifiers. Particularly, whether or not there is any validity to the assumption that manufacturers consider them as an afterthought. Somewhere in this thread,

http://www.head-fi.org/forums/f5/man...-jacks-338299/

I mentioned that I was going to be taking ownership of the Onkyo A-9555 integrated amp. Well, I finally got around to comparing its headphone out to my also recently acquired HeadAmp GS-1. For good measure, I also compared the headphone out of my Onkyo DX-7555 CDP, which is a companion to the A-9555. Please be forewarned that I am not going to bog you with detailed descriptions of how each sounds. The purpose is to demonstrate whether or not the two Onkyo products can drive headphones as well as a dedicated headphone amp.

For comparison purposes, I have the CDP feeding the GS-1, and using the GS-1’s loop out to feed the A-9555. All are connected with Kimber Timbre interconnects. This allowed me to do direct comparisons between the three. Headphones used were the Grado RS-1 and Sennheiser 580 with Equinox cable. Song selections from various musical genres were played. Here is a pic of my set up.



Note that the little clock radio-like device next to the GS-1 is a tuner, some of my comments on which can be found here.

http://www.head-fi.org/forums/f7/sony-xdr-f1hd-351803/

First, a few words on the equipment used. Both the CDP and A-9555 are extremely well built, solid components. While certainly not high end (although Onkyo describes the CDP as audiophile-grade), there is nothing cheap or flimsy about them. The A-9555 in particular, is fairly heavy as well as large (and made in Japan). It just barely fits on the shelf of my stereo stand. Considering its size, you would expect it to have a lot of power. It also runs quite warm when turned on. I don’t know how the headphone outs are designed on the Onkyos - whether it’s off the resistors or op amp based. TFarney indicated he knew but wouldn’t disclose the answer. Hopefully he will now. Enough has been said about the GS-1 in other threads. The specs for all are linked below.

Onkyo DX-7555 - Audiophile-Grade CD Player | Model Information | Onkyo USA Home Theater Products

Onkyo A-9555 - Integrated Digital Amplifier | Model Information | Onkyo USA Home Theater Products

HeadAmp - Audio Electronics (GS-1 Headphone Amp/Pre-Amp)

We’ll start with the CDP. If I had never heard a headphone amp before, I would probably be satisfied with the headphone out on the CDP. Both the RS-1 and 580 sound great directly out of the DX-7555. It’s a strange beast though, because you really need to increase the volume knob in order to get sufficient volume out of the RS-1. I think Greggf had mentioned this in one of his posts regarding this CDP. The headphone out actually drives the 580’s slightly louder than the RS-1.

When comparing the headphone out of the DX-7555 to the GS-1, the biggest difference is that the GS-1 is a little more punchier and the bass a little more tighter. Note though that the difference is not drastic and noticeably more so with the 580s and noticeably even more so only with certain recordings.

The A-9555 did very well against the GS-1. It was very hard to discern differences between the two. If there was one drawback, I would say it goes too loud and you need to really keep the volume in check. Occasionally, the bass on the A-9555 would sound a little bloated or boomy compared to the GS-1. Ultimately though, if I had to depend only on the A-9555 as a headphone source, it is more than satisfactory and I would have no problems using it.

However (and take this with a grain of salt), when simply just listening to each unit on its own without trying to do an analytical compare, I seemed to get a more pleasurable listening experience from the GS-1. This especially held true with better recorded material. Placebo? Who knows? Regardless, one advantage the GS-1 has over the Onkyos is that it does handle bass a little bit better. I’m thinking the GS-1s’s capability to select either high or low gain plays a factor in this, and a gain feature is always something useful to have.

I must admit though that after a while, everything kind of became a big blur and I tried to hear differences that may or may not have been there. Obviously, given that my most expensive piece of gear is the GS-1, I wanted it to be the clear winner. Well, the results are not so clear (or more appropriately, not so overwhelming) but I reached the decision that it was the winner. Whether this is placebo or not is something I’ll have to reckon with

A few caveats that should be mentioned:

1. I don’t know if it would have made any difference if I had the CDP feeding the A-9555 directly instead of going through the GS-1 loop out. If anyone thinks this is worth trying, let me know although I won’t be able to do an A/B comparison.
2. The A-9555 does have bass and treble controls. For comparison purposes though I left these as neutral (i.e in the center setting). It also has “pure direct” option which bypasses the tone controls “so you can enjoy pure sound.” I left this setting off as well.
3. Synergy may play a big factor with the A-9555. Another CDP may not sound as good with the A-9555 and vice versa.

So what conclusions to make from this? Are the Onkyo headphone outs just as good or almost as good as the GS-1? Are headphone amps overrated? As I certainly don’t consider myself an audiophile, maybe I just don’t know what I’m supposed to be listening for. I can only report what my ears heard.

As always, all of this is subjective and YMMV.
post #2 of 32
Great comparison.

Were you able to do any type of volume matching. IMO this is the hardest part of comparing amps. From what I've read, a 3dB difference in volume can produce a noticeable effect in the perceived FR, especially in the bass and to a less extent in the high end. A lot of times, when people prefer one amp over another in a listening test, they prefer the one that is being played louder.

I try to volume match with a 1K tone, some times by ear, sometimes with an SPL meter using the plate method (http://www.head-fi.org/forums/2767153-post42.html)

Not knowing how accurate this measurement is, and by ear is not accurate, if I hear a difference in the bass, I purposely adjust to volume to do listening tests with one amp louder, then switch to do the test with the other amp louder.

I also do the same thing when comparing headphones since volume matching 2 headphones from one jack is impossible, at least for me.
post #3 of 32
Quote:
quite warm when turned on. I don’t know how the headphone outs are designed on the Onkyos - whether it’s off the resistors or op amp based. TFarney indicated he knew but wouldn’t disclose the answer. Hopefully he will now.
I'd be happy to discuss it if I had an answer. I did a little follow-up to odigg's original integrated amp research and wrote a few manufacturers I'm personally interested in. If I remember correctly, Onkyo didn't get back to me. Maybe odigg has the answer.

I suppose the Onkyo may have done a little better if it hadn't gone through the GS-1's loop, hadn't involved an extra pair of interconnects, and had the tone bypass been turned on. I seriously doubt you would hear much of anything, but theoretically all that wire has an effect on resolution and noise. Then again, it could simply be that a $900 dedicated headphone amp has a bit better bass control than the headphone section of $500 integrated amp. It certainly should.

Thanks for the report.

Tim
post #4 of 32
zotjen,

Wonderful job!

There is a brilliant classic post, many moons ago, from Jan Meier, which I don't have the link for. Hopefully it's still findable. Anyway, Mr. M. of Corda amp fame suggests that it's in the bass that dedicated amps shine. I believe he says that it's because they tend have lower output impedances than equipment jacks.

But he goes on to say that many may prefer the looser bass of those standard jacks, and that it's not a matter of right-or-wrong or better-or-worse, just a matter of taste.

It was quite a balanced statement, as I recall, and quite a pleasant surprise to me.
post #5 of 32
There are some pleasant surprises out there among the built-in commercial headphone jacks/amps. If I remember correctly, markl used to drive his R-10's out of a headphone jack on a Denon(?) component since he liked it as much as the amps he'd tried. I think the biggest problem is the haphazardness of which components have good jacks and which do not. Some of the old Denon product lines used to have some mid range components with good amplifiers while their high end components did not. there just doesn't seem to be a great way to determine it without buying both and comparing them.
post #6 of 32
Quote:
Originally Posted by zotjen
I don’t know how the headphone outs are designed on the Onkyos - whether it’s off the resistors or op amp based.
I am not absolutely certain, but since the A-9555 is a digital amp for the speaker taps, which does not normally permit shared grounding, I'd venture a strong guess that the headphone jack has a separate op-amp circuit. Neither here nor there though, as the final result is all in the implementation.

Thanks for taking the time to perform your comparisons & write them up. I always enjoy when members come up with alternative solutions, or showing that more is not necessarily that much better.
post #7 of 32
Quote:
But he goes on to say that many may prefer the looser bass of those standard jacks, and that it's not a matter of right-or-wrong or better-or-worse, just a matter of taste.
It is, indeed, a matter of taste, and Dr. Meier showed a lot of class in saying so. There is this space between bloom and boom where, to my taste anyway, mid-bass sounds not only better, but more natural than it does when it is under very tight control. Too loose is just plain messy. Too tight often misses, in controlled studio recordings, the natural bloom of a bass live in a lively room.

Tim
post #8 of 32
Yes. I find I prefer a less tight bass; it matches what I hear in the concert hall a little better.
post #9 of 32
Tight bass. Tight ass. Accept no substitutes!
post #10 of 32
Quote:
Originally Posted by gpalmer View Post
There are some pleasant surprises out there among the built-in commercial headphone jacks/amps. If I remember correctly, markl used to drive his R-10's out of a headphone jack on a Denon(?) component since he liked it as much as the amps he'd tried. I think the biggest problem is the haphazardness of which components have good jacks and which do not. Some of the old Denon product lines used to have some mid range components with good amplifiers while their high end components did not. there just doesn't seem to be a great way to determine it without buying both and comparing them.
Yes, the former Denon flagship.. The model was replaced by the 5308CI, which was later replaced by the AVP-A1HDCI.
post #11 of 32
Thread Starter 
Quote:
Originally Posted by scompton View Post
Great comparison.

Were you able to do any type of volume matching. IMO this is the hardest part of comparing amps.
No, I didn't do any volume matching (which I think is a valid concern) but I did some comparisons at different volume levels (e.g. blasting as much as my ears could stand, barely above a whisper, etc.).

Quote:
However (and take this with a grain of salt), when simply just listening to each unit on its own without trying to do an analytical compare, I seemed to get a more pleasurable listening experience from the GS-1.
To expand on this point I made (or maybe reaffirm it), yesterday I listened to a CD I hadn't heard for quite some time. When it was over I noted to myself that I didn't enjoy it as much as I should have. I then realized I had inadvertently plugged my cans into the headphone out of my CDP instead of the GS-1.
post #12 of 32
Quote:
I think the biggest problem is the haphazardness of which components have good jacks and which do not.
I think this may be the remaining un-debunked myth. I mean we certainly don't have a statistical sample of reporting on the board in the last couple of weeks, but from what we do have, one could very quickly conclude that with a few odd exceptions like the Denons you mentioned, the quality of the headphone sections of receivers and integrateds falls right in line with the quality of the receivers and integrateds that contain them. That's not haphazard at all.

Tim
post #13 of 32
Quote:
Originally Posted by tfarney View Post
I'd be happy to discuss it if I had an answer. I did a little follow-up to odigg's original integrated amp research and wrote a few manufacturers I'm personally interested in. If I remember correctly, Onkyo didn't get back to me. Maybe odigg has the answer.

Tim
Sorry for the late reply. I'm not following head-fi as much as I used to.

The A-9555 uses a dedicated opamp circuit for the headphone jack. I found this out by hunting down a schematic for the amp. Onkyo took a long time to get back to me and left out any mention of the A-9555.

This supports another theory stated here and in other threads that Class D amps have some issue with using resistors off the main amp. Probably, as stated, an issue of shared ground.
post #14 of 32
Quote:
Originally Posted by zotjen View Post
There's been a lot of talk recently regarding the headphone outs on integrated amplifiers. Particularly, whether or not there is any validity to the assumption that manufacturers consider them as an afterthought.
OP, I know you wrote this months ago and will probably never read this reply, but I want to sincerely thank you for this. As the proud owner of an Onkyo A-9555 (since before I started getting into headphones), I have been wondering whether I need to purchase a dedicated headphone amp. Now I don't have to worry about that so much and can buy a pair of AKG K 701s instead.

I always thought my headphones sounded great out of the Onkyo, but how would I know? Thanks. You rock.
post #15 of 32
The Onkyo amps do have very decent h/a output, my onkyo 805 gives many SS amps a pretty good run for there money.

Listen to your ears!
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