[Armaegis]

I tried doing a search but didn't see this mentioned... Does plugging in headphones turn off the RCA output?

 

[kite7]

Quote:

Originally Posted by Armaegis /img/forum/go_quote.gif I tried doing a search but didn't see this mentioned... Does plugging in headphones turn off the RCA output?

Yes it does

 

[Fantoon]

does it hiss with the westones (3 & UM3X) ?

 

[HeadphoneAddict]

Quote:

Originally Posted by Fantoon /img/forum/go_quote.gif does it hiss with the westones (3 & UM3X) ?

I mentioned this in post #1 or #2, but no, for me the HDP is silent with all my custom IEM and universal IEM.

 

[bcwang]

Quote:

Originally Posted by Fantoon /img/forum/go_quote.gif does it hiss with the westones (3 & UM3X) ?

And for me, the answer would be yes, it hisses. It all depends on your hearing sensitivity though. It would seem to most people it does not hiss even with westones. However, if you are sensitive to hiss with your headphones and most amps/sources you've tried, you will probably hear hiss with the HDP.

 

[HeadphoneAddict]

Quote:

Originally Posted by bcwang /img/forum/go_quote.gif And for me, the answer would be yes, it hisses. It all depends on your hearing sensitivity though. It would seem to most people it does not hiss even with westones. However, if you are sensitive to hiss with your headphones and most amps/sources you've tried, you will probably hear hiss with the HDP.

Can you list what amps do and do not hiss with IEM for you? That would help as a frame of reference for others, since you were able to hear incredibly low measured voltage levels of pink noise when you visited Nuforce (0.00004v into the 100kohm input of the analyzer).

I'm not immune to hearing hiss with certain amps, with APM3 being the noisiest > SAC KH1000 > Behringer UC202 > ALO Amphora which are all worse than Macbook Pro headphone out (which has some hiss too). But for me the remainder of my huge list of amps are fairly quiet with the volume knob set anywhere in the normal listening range that could be used with an IEM.

 

[bcwang]

Quote:

Originally Posted by HeadphoneAddict /img/forum/go_quote.gif Can you list what amps do and do not hiss with IEM for you? That would help as a frame of reference for others, since you were able to hear incredibly low measured voltage levels of pink noise when you visited Nuforce (0.00004v into the 100kohm input of the analyzer).

Sure can. And by hiss, I do mean at regular listening volumes only, even minimum volume. All of them hiss if you turn up the volume with no music playing.

With Shure SE530

No detectable hiss:
-tomahawk
-(maybe) I want to say sl-sx500 as I never remembered it hissing, but I also didn't have many of my current IEMs when I was actively using it. I do know when I went to the ct570 it was an immensely noisy headphone jack in comparison. If I can find it I can re-verify this statement.

Hiss:
-XP-7 with ad825 (very loud hiss)
-XP-7 with AD-797 (pretty low hiss)
-Grado RA-1 (very loud hiss)
-Nuforce HDP (pretty loud hiss)
-Nuforce uDac (pretty low hiss)
-Xin Super mini v4
-total airhead
-Iphone 3gs
-Ipod 5g
-panasonic sl-ct570(very loud hiss/buzz)
-archos 605 (very loud hiss)
-turtle beach audio advantage (very loud hiss)

 

[SleazyC]

Hey Larry, have you tried the HDP out with your ESW10's yet? I'm curious to see if they make any marked improvement or just improve them slightly as many other amps do.

 

[HeadphoneAddict]

Quote:

Originally Posted by SleazyC /img/forum/go_quote.gif Hey Larry, have you tried the HDP out with your ESW10's yet? I'm curious to see if they make any marked improvement or just improve them slightly as many other amps do.

Although the ESW10 perform well without an amp, I've always preferred mine with an amp, and the HDP is no exception. It helps me get more out them than just using my iPhone or Macbook headphone out.

 

[bcwang]

Your 300 hour mark should be coming up soon. Can't wait to get your full impressions.

 

[HeadphoneAddict]

Quote:

Originally Posted by bcwang /img/forum/go_quote.gif Your 300 hour mark should be coming up soon. Can't wait to get your full impressions.

I have been posting my listening updates often in post #2, so be sure to take a look there. Basically the HDP headphone amp is great and at less than 10 hours it was clearly better than the prototype which I returned to be updated. The HDP headphone amp is probably on the level of (and reminds me of) the $690 Grahm Slee Solo SRG II that I borrowed and reviewed just a month ago; and it's only slightly below my $1250 maxed Woo WA6 with RCA 6DE7 and Sophia Princess 274B, or my $995 ALO Amphora headphone amps.

The WA6 and Amphora have a little more depth of stage and soundstage size, and a touch more refinement and transparency, among other things; but the HDP headphone out is surprisingly close for a much lower price. This is whether using my HD800, HD600, HF-2, HE-5, or IEMs. I actually prefer the HDP for the HE-5 because it seems to have more power than WA6 and Amphora now, rather than less like the prototype had with these phones.

And, while the Solo SRG II was not a good choice for IEM because of noise and high gain, the HDP is perfect for all of my IEM, universal or custom. My UE11Pro are very picky about what amp I use with them in order to control the bass and fill in the mids, and the WA6 has always been my best amp for them. But the HDP headphone amp is almost as good as the WA6 with the UE11Pro, and it actually beats the Amphora when using the UE11Pro (Amphora also has much more hiss than HDP with IEM).

The HDP as a desktop amp beats all of the portable DAC/amps that have come through here now or in the past, including the DACport which comes close, or my opamp rolled iBasso D4 and D10 which are slightly farther back but also quite good. It almost seems like the HDP's $449 price is reasonable for the DAC, and the $449 price is also reasonable for the headphone amp, and somehow we get both for the same low price. In my book that makes it a best-bang-for-the-buck purchase.

What I am focusing on right now is the HDP as a DAC feeding my other amps, and comparing it to my Apogee mini-DAC, and then my PS Audio DLIII. That is taking me more time than I had planned.

 

[bcwang]

Quote:

Originally Posted by HeadphoneAddict /img/forum/go_quote.gif What I am focusing on right now is the HDP as a DAC feeding my other amps, and comparing it to my Apogee mini-DAC, and then my PS Audio DLIII. That is taking me more time than I had planned.

Take your time, don't rush the comparison. The more thorough the better.

And funnily, as we all talk about hiss, it seems to be all relative to the listener.

-Your comment: "Amphora also has much more hiss than HDP with IEM"

-A review on the amphora I was just reading: "
What I also cannot talk about is noise. Because here again, there simply isn’t any. It just isn’t possible to ask an amp to be quieter, or have a blacker background, than the Amphora. In this regard, it is, I believe, the best I have ever heard. Tubes always involve at least a little bit of hiss at the very top of the amp’s volume range. There is nothing of the sort here, and it’s also quieter than any of the SS amps I have around. This may well be due to the battery operation – not sure. But it sure is one silent runner."

Haha, I think agreement on the noise level of an amp is hard to achieve.

 

[jasonl]

We have spent the past 3 days to look over HDP (more testing before a big production), and also to determine if there is any way to optimize it both for IEM and high impedance headphones so that people like bcwang with very sensitive ears can avoid hearing the noise floor with IEM. The conclusion is that HDP has to be optimized for headphones as our original design goal. We think IEM will still sound awesome if you can not hear the noise floor being detected by sensitive IEMs.
We have published this technical note about the noise floor:
Nuforce.com | Guides
It is not due to the SMPS so there's not much we can do about it unless we compromise our design goal to lower the gain of HDP to suit IEM.

We will start taking orders for HDP starting 2/26.

 

[Hygienist]

HPA,

Thanks for taking the time to be so thorough! I'd just like to ask, in your review of the DACport you said using that as a DAC/Amp, compared to the HDP used as a DAC/Amp, the DACport was only of slightly less quality. Do you still stand by this assertion (especially when used with IEMs, such as JH13), or has the revised unit changed your opinion?

 

[Poetik]

Quote:

Originally Posted by HeadphoneAddict /img/forum/go_quote.gif The HDP headphone amp is probably on the level of (and reminds me of) the $690 Grahm Slee Solo SRG II that I borrowed and reviewed just a month ago; and it's only slightly below my $1250 maxed Woo WA6 with RCA 6DE7 and Sophia Princess 274B, or my $995 ALO Amphora headphone amps.

I think that alone just pushed me over the edge to buy this thing.