Ok, I've tried, but I'm stuck. I didn't know where to ask this question and it seemed like the DIY community here would have the largest number of technically knowlegable people who aren't going to spout a lot of nonsense. My dad was an EE, but I'm completely out of my depth here. Any advise and/or clarification would be much appreciated.
I read a few places that low impedance iems could be run very well directly out of certain dacs without an amplifier and sound fantastic because of the lack of degredation, etc.
First off, is this true? What, if any, are the potential things to look out for in running a dac directly to a headphone and controlling volume in the digital domain?
For my setup, I have a macbook pro using a toslink to 1) an eastern electric minimax tube dac, or 2) a yulong d100 dac; or a usb to a 3) dacport lx.
My only headphones are the JH13's, which have 29 Ohm impedance.
I've been trying to get the line out specs, but it seems like everyone lists them partially or not at all.
The dealer told me that the minimax has a 200 ohm impedance out using the solid state and 2000 ohm using the tube.
There's no listing for the D100 line out specs.
There's no listing for the Centrace Dacport LX because this http://centrance.com/products/dacport/ is for the regular amped dacport. The only thing they list that I know is for the LX is that the output is "+6dBV" (??!??)
The modder of the hiface, John Kenny, has said that his new sabre-based JKDAC can drive a range of headphones directly without an amplifier, and he seems to like that idea, but he doesn't list the specs for the unit. I've asked him, and am waiting to see what he says.
In terms of my own tests, the dacport lx to JH13 is incredibly loud and usually needs to be attenuated about -20db. It sounds incredible in the mids and highs, but lacks a bit of bass.
The Yulong D100 line out to JH13 sounds clearer and less muddy than the low impedance amp output, but it too lacks a bit of bass power and articulation. It is also on the quiet side, being almost a perfect match without any attenuation at all, but a bit too quiet on some classical recordings.
The EE minimax doesn't work with the JH13s. It's too quiet even on the SS, and the tube output is practically inaudible. Plus there seemed like there might be some distortion, so I didn't continue testing. Obviously a mismatch.
The only amp I currently possess is the ibasso T3D, which is ok, but obviously not a stellar amp. It does pretty much what the amp on the yulong does - thickens, darkens and muddies the sound, giving more bass presence and removing lots of detail and articulation.
I have a Pico Slim amp coming next week to test, and they list the following:
- Signal-to-Noise Ratio >100dB
- Total Harmonic Distortion 0.003%
- Gain up to 2x/6dB
- Input Impedance 10K ohms
- Output Impedance less than 1 ohm
- Output Voltage 4V peak-to-peak, 1.4Vrms
- Output Power 0.35Wrms w/ 32 ohm load
I read somewhere about a 8x impedance rule? So 29/8 would be less than 4 ohm output impedance as ideal for the JH13s? If that's the case, the 1 ohm output seems good, but could I even hook this up to the Minimax, given that it has a 200 ohm output and the imput here is listed as 10 ohm? What is the power and voltage mean on this? I've seen output power at 32ohm ranging from .35w to .9w or higher - is there some number I should be shooting for? Just the more the better?
I'm guessing the dacport lx will work best with the pico slim, and I know the pico slim sounds incredible with the JH13, because I used to own one, but that's not really what I'm interested in. I wanted to see if I could use all my money on a really good dac instead of splitting it 50/50 between a lesser dac and a lesser amp. And I don't want to get an amp (or a dac/amp) that is mainly for 600 ohm headphones and just added on low impedance as an afterthought, because these are my ONLY headphones, and I have no interest in driving the HE-6 or the LCD-3.
If anyone could lend a hand with these numbers, I'd really appreciate it. Thanks!
-andrew
