[matthewh133]

Anybody have any experience with the HDP and a set of ATH-AD900s? I recently got my new headphones and looking for the right new amp/dac that has great synergy with my headphones. Any assistance would be greatly appreciated!

 

[Sid-Fi]

I'm in the same boat as HeadphoneAddict with my HDP. It feels totally silent and black with my IE8 and HD650 as well as my wife's IE7. I am really loving this thing. It is a very significant step up from my topkit D10 in all areas.

 

[cravenz]

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I've got my Westone ES5 customs plugged into the HDP right now using the 24/96 USB DAC, and I cannot hear any hiss with it anywhere from volume off, to zero volume, to max volume.  I put on Bink Audio test CD with a silent track #59 and even when playing and not paused the HDP is quiet at any volume.  
 
This is one of the original 20 production HDP that still has the 3.5mm analog jack's channels swapped, but that should not make a difference.  It's not been a big enough deal for me to want to send it in, so they sent me a corrected PCB which I still need to install.

 
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I'm in the same boat as HeadphoneAddict with my HDP. It feels totally silent and black with my IE8 and HD650 as well as my wife's IE7. I am really loving this thing. It is a very significant step up from my topkit D10 in all areas.

I've just tested the HDP with my Sony MDR-EX71s, the hiss is definitely less, but it is still there and microphonic issues when shifting the volume pot as well. I didn't test it pass 12 o'clock.
 
Also, another issue that I'm facing is channel imbalance. Against my greater judgment, I'm using my 702s with it to evaluate the DAC (this testing was done with the volume dial at 12pm vertical); I've tested it with several songs and had a friend listen to it as well without telling him if there was any channel imbalance and he immediately noted that the left side was louder. We both noted that after a while we would get used to it somewhat, but for me its more my brain and trying to convince myself that it's fine because in every song, the vocals are always off centre.
 
If I had to draw a line to show what the sound feels like, it would be from my nose outwards, it would be a diagonal line from my nose to my eye and upwards and the area in between would be where the vocals would be around. Even if I force myself to try to somehow listen through my right ear only, it's the same thing. The weight/balance just seems off. To eliminate any doubt, I've switched my 702s around (left side of the headphone to my right ear and vice versa) and I still have the same issues. To put the nail in the coffin, I switched back to my D10 to M-Stage and I don't have that issue, so I am 100% sure of channel imbalance and the unit is going back. I do like the DAC and I like the unit as a whole, but I'm really sure there is something wrong with my unit now and this has cast some doubt as to the cause of the IE8 meltdown being the IE8 just coincidentally dying off or me playing around with the volume pot and without any music.
 
Anyhow, this is just my experience. If that channel imbalance issue is normal, then I will definitely ask for a refund because it drives me crazy. Also, I'm still awaiting a reply from NuForce. I'll probably ship this off tomorrow or the day after as I'm stuck with so much university work at the moment. I was hoping this would accompany me through it all. And please don't anyone think I'm hating on the product. I really like the unit, I just honestly believe I have a faulty product, but I'm open to correction otherwise.

 

[Sid-Fi]

When vertical, the volume knob on my HDP is at 8am when switched on. I have channel imbalance for only a tiny sliver of the dial, until around 8:20 am. After that I have no hiss or background noise at all and the volume dial is completely silent thereafter when adjusting volume.
 
My recollection from most of the user comments I have read from HDP owners is that the worst cases of channel imbalance are usually only until 9 am on the dial (vertical). Most of the comments of channel imbalance that I read were pretty early-on so I just assumed they ironed this out by the time I ordered mine.  
 
It sounds like your unit has channel imbalance at least until noon on the dial when vertical? If so, that definitely does not sound normal.

 

[cravenz]

Quote:

When vertical, the volume knob on my HDP is at 8am when switched on. I have channel imbalance for only a tiny sliver of the dial, until around 8:20 am. After that I have no hiss or background noise at all and the volume dial is completely silent thereafter when adjusting volume.
 
My recollection from most of the user comments I have read from HDP owners is that the worst cases of channel imbalance are usually only until 9 am on the dial (vertical). Most of the comments of channel imbalance that I read were pretty early-on so I just assumed they ironed this out by the time I ordered mine.  
 
It sounds like your unit has channel imbalance at least until noon on the dial when vertical? If so, that definitely does not sound normal.

Yup, I experienced channel imbalance at least until noon and max 1 pm on the HDP with the 702s plugged in and with the HDP vertical. My friend felt that it was less obvious on the IEMs, but it was stark in comparison on the 702s. Also, my friend has no prior knowledge of audio equipment and had no knowledge of this channel imbalance issue prior.

 

[crumpler]

Yea, i've never experienced channel imbalance after the 9 o'clock position with the HDP vertical so you should definitely send it back to NuForce!

 

[bcwang]

Channel imbalance up to 12 o'clock sounds like a defect to me.  You probably have a bad volume pot.  Send it back for another unit!

 

[cravenz]

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Channel imbalance up to 12 o'clock sounds like a defect to me.  You probably have a bad volume pot.  Send it back for another unit!

Yeah, I'm definitely going to do that. I still haven't got a reply since Thursday from them and I just sent them another mail (10 hours ago approximately) asking about what to do and what form of shipping to use? Anyone have any idea? I've never had to ship a product back ever. Problem is, normal Airmail would cost me 60AUD already apparently and to have it tracked would cost approximately 80 bucks. FedEx is out of the question, got quoted 160AUD lol. Do you guys also end up insuring the item, etc.

 

[goldmbe]

Using the AKG 701's with the HDP, I have the feeling that they are somewhat underpowered when I listen to some classical music albums (particularly those mastered during the pre-loudness war era of the mid-1980's). For instance, I've been listening to Riccardo Chailly's 1985 recording of the Bruckner 7th Symphony for the last couple hours and have been getting increasingly disappointed with its harsh, dry and thin sound and general lack of impact, for lack of a better term. I tried testing with my two other headphones, Senn HD600 and Grado SR-60i, to see if I could get a lusher tone, but...compared to the AKGs, both cans sounded so dark, even "muddied" to me that I couldn't stick with them for long before going back to the 701s.
 
I also have a uDAC and actually wound experimenting by connecting the uDAC to my iMac via USB and then connecting the analog out on the uDAC to the analog in on the HDP via RCA cable and then plugging in the 701s into the HDP headphone jack. Playing the tracks on the album while switching back and forth between the analog and digital (HDP also connected to iMac via Toslink) outputs on the HDP resulted in what seemed to me to be a striking superiority in both the musical richness/depth and loudness of this "uDAC/HDP combo." But I'm not going to keep this configuration for long because I want to make use of the DAC in the HDP. So I'm wondering if anyone else with the 701s and the HDP has experienced this power issue and also if connecting the HDP to a dedicated headphone amp would be beneficial. I was browsing Musical Fidelity's website and looking at the V-Can and the X-Can; anyone know if either of those would possibly work well with the HDP for very hard to drive cans like the 701s?

 

[cravenz]

Quote:

Using the AKG 701's with the HDP, I have the feeling that they are somewhat underpowered when I listen to some classical music albums (particularly those mastered during the pre-loudness war era of the mid-1980's). For instance, I've been listening to Riccardo Chailly's 1985 recording of the Bruckner 7th Symphony for the last couple hours and have been getting increasingly disappointed with its harsh, dry and thin sound and general lack of impact, for lack of a better term. I tried testing with my two other headphones, Senn HD600 and Grado SR-60i, to see if I could get a lusher tone, but...compared to the AKGs, both cans sounded so dark, even "muddied" to me that I couldn't stick with them for long before going back to the 701s.
 
I also have a uDAC and actually wound experimenting by connecting the uDAC to my iMac via USB and then connecting the analog out on the uDAC to the analog in on the HDP via RCA cable and then plugging in the 701s into the HDP headphone jack. Playing the tracks on the album while switching back and forth between the analog and digital (HDP also connected to iMac via Toslink) outputs on the HDP resulted in what seemed to me to be a striking superiority in both the musical richness/depth and loudness of this "uDAC/HDP combo." But I'm not going to keep this configuration for long because I want to make use of the DAC in the HDP. So I'm wondering if anyone else with the 701s and the HDP has experienced this power issue and also if connecting the HDP to a dedicated headphone amp would be beneficial. I was browsing Musical Fidelity's website and looking at the V-Can and the X-Can; anyone know if either of those would possibly work well with the HDP for very hard to drive cans like the 701s?

I'll just comment briefly on my short stint with the HDP and 702s I have, though bear in mind that I am experiencing channel imbalance issues.
 
I didn't listen to classical music during my testing and mainly listened to some chinese popular music and english popular music. Volume definitely came out decently well, but yes, I do feel that they are underpowered and the output seemed a little shrill/thin so I can imagine the sound with classical. But I definitely can see why this pairs up well with the HD650s. I can't compare this experience to analogue out of the HDP until the Transient cable from them reaches me, but even when it does, I won't have the HDP in my possession.
 
I usually have my 702s hooked up to my D10 and M-Stage and feel that the M-Stage is certainly more laid back and feels like it drives the 702s without a hitch and without any issues. I did feel that the DAC side of the HDP brought up the music notes better and I felt that I could actually get some semblance of the sub-bass. I can only imagine this being better in the HDP. Again, this is an inaccurate test as I am unable to isolate the HDP as a DAC and will be sending back my unit, but hope that helps a little.

 

[cravenz]

for those that are wondering, basically, NuForce sets out that the reason for the hiss here and is also part of their response (I'm actually glad I finally got a response to be honest): Noise Floor
 
I don't believe I have very sharp ears cos' I frequently have people calling out to me and I never know this, but hey.

 

[cravenz]

just a quick update, NuForce have responded on the channel imbalance issue and it looks like they will replace my unit.

 

[HeadphoneAddict]

Quote:

just a quick update, NuForce have responded on the channel imbalance issue and it looks like they will replace my unit.

That's great - it's too bad yours didn't work right, but it's a good value for the price.  I was quite surprised to be browsing the Meier Audio website the other day and seeing Jan Meier selling the HDP which competes with his own products, but he was endorsing it right on his own site!

 

[cravenz]

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That's great - it's too bad yours didn't work right, but it's a good value for the price.  I was quite surprised to be browsing the Meier Audio website the other day and seeing Jan Meier selling the HDP which competes with his own products, but he was endorsing it right on his own site!

Yup. I definitely think it fits all the needs I have at this point in time. I think the HDP is a great product for what it is. I just think it was plain bad luck to have everything go wrong at the same time which soured the experience

 

[HeadphoneAddict]

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Yup. I definitely think it fits all the needs I have at this point in time. I think the HDP is a great product for what it is. I just think it was plain bad luck to have everything go wrong at the same time which soured the experience

I have two HDP here and will be sending one of them to Skylab very soon for his impressions, once he catches up on a couple of other reviews - we discussed doing this last month.  Even if he finds that it sounds like any other $400 amp that he's tried, it's almost like getting a free DAC when you buy one to use as an amp (and visa versa).  I suspect he'll say that it comes in below his Woo WA6 like I did, but he should still find it to be a very good match for his HE-5 LE and his LCD-2.