Review: ZERO 24 BIT/192KHz DAC/Headphone Amp/Pre-Amp - Page 595

since there are a lot of experienced dac modders in this thread, i'd like to draw a bit attention to my thread about my problems with installing an OPA module in my constantine dac.
http://www.head-fi.org/forums/f7/con...5/#post5647005

Does sound like you have a ground loop issue.


.

I currently have dual 627s for the DAC and LM4562 for the preamp, I just ordered some LME49860NA samples...

Anyone tried these for the preamp??

my Zero died really soon too when I got it, I wouldnt recommend it to anyone anymore, its not the great product it was when the review was written

I haven't had an ounce of problems with mine. It handles all my Hi-Fi, TV, radio, DVD sound needs. And as such is on for at least 12 hours a day, for the last nearly 18 months.

Sorry to hear you've had problems with yours, but for the price I can't fault mine.

Before Compass Zero was the best DAC combo for headphones for the money. I just recomissioned my Zero to my workplace after getting a Compass.

Hey guys. After doing a little research, I ended up with one of the Zeros and... WOW!

I can't believe the difference. Listening to Queens of the Stoneage - Little Sister. There was so much detail, even in the 192kbps mp3's that I was missing. The mids are so much more detailed, the bass has more impact and clarity. The trebble is less overbearing because of the added detail provided at the other frequencies.

Edit: I went straight for the OPA627 and LT1364 combo (as per signature) so I haven't heard the original zero. The upgraded one is phenomenal though.

interesting

I'm using the Zero with the Earth-HDAM and 2xLM4562 and this is a very nice combinations with the K701s as it sounds quite "warm".
But i noticed that the Zero doesn't have another power to drive the K701s properly, as i can turn the volume knob up to 4o'clock without getting blown away (this is probably current-related, but i'm not an electrotechnical engineer).

I had no idea the 701s required so much to run? My Zero runs the HD650s great. What is the impedence of the 701s?

.

Despite their low impedance (not sure but I think they are 62ohm) the 701s are notorious for being very difficult to amp properly. Don't quite understand why, but that's the general consensus.

So 62 ohm Headphones can require the Zero to be twisted to 4:00 on the dial? I haven't listened to my Zero in a while but this seems strange. I never felt my Zero was low on Gain. That's amazing!

.

It's actually quite easy: If you apply the same output voltage to a high and a low resistor (e.g. 600Ohm HD650 vs. 62Ohm K701), you will get as a result low and high current, because I=U/R. So with low impedance cans the amp has to supply a high current. I suppose that could be part of an explanation, why the K701s are hard to drive.

Edit: Normally my volume knob is between 10 and 12 o'clock. I just tried to turn it beyond 12 o'clock to see how far it can go. It gets quite loud at 4 o'clock, but it's not unbearable and i hear no distortion.

Well, I understand what you are saying, but here's my experience that I'm using and why what you said makes no sense to me. Except for Scotties Explanation.

First The HD650s are 300 ohm. Just wanted to correct that.

I have lots of low impedance cans, Denon, Grados, 80 ohm beyers, DX1000. None of them are difficult to drive for the Zero, "that I remember".

But I may hook it back up, I need to work on it anyhow.

I'm not sure there's a spec for sensitivity in Headphones, just like in speakers, just don't remember seeing it. That would explain it.

.

Yeah my explanation wasn't even about the LOUDness, per se, just that to sound GOOD the 701s seem to need a good amp. But I've only ever heard them a few times and have never owned them, so this is just what I'm told. Even with my HD600s (also 300ohm) the Zero was plenty loud.