[david1rest]

Hi,
i recently bought an Audinst MX2 (dac amp combo). Worth ****** gold for me, especially with my easytodrive Sennheiser HD518.
 
But now i upgraded from the Senn to the DT990 pro. Even more gold, but the point is that these cans are 250 ohm, therefore not as easytodrive.
 
I then bought an relatively cheap amp (Pro-ject HeadBox S). Thought it would give my Sytem more Juice, but once i hooked it up to the DAC via the RCA cables
the sound was really quiet. I had to put the volume knobs up to 3 oclock, on BOTH machines, and my Laptop volume to a frickin 100 percent.
 
(i already changed the Gain jumpers in the Audinst to 300-600 ohm support, instead of their default 30-300 ohm).
 
would be thankful for any help
 
PS: i also put the dac and amp both at DC power and also tried it without....no real difference. problem stays the same.

 

[billybob_jcv]

So - you are going from the PC USB port to the MX2, and then the MX2 RCA lineout jacks to the pro-ject RCA line-in, is that correct? If that is the case, then it's correct to put the PC volume and the MX2 volume to max and just control the volume with the Pro-ject.

When you are doing it this way, you are bypassing the amp in the MX2 and relying solely on the Pro-ject amp. This is good for providing the cleanest possible signal to the Pro-ject. However, the question then becomes: Does the Pro-ject have adequate power to drive the DT990 Pro? The spec I saw said that it has a gain of 11 and can put 60 millivolts into 300 ohms. I couldn't find the spec for the Audinst. It's certainly possible that the output of the MX2 amp is approximately the same (or even more) than the Pro-ject. They are both good, solidstate headphone amps.

What you *could* do is daisy-chain the amps together to get more gain. This is usually not recommended because it increases the noise - but it can certainly be done with good, low-noise amps. To do this, instead of using the line-out of the MX2, use the headphone out. Feed the headphone out from the MX2 into the RCA line-in of the Pro-ject. Adjust the volume of the MX2 to be in the midrange, then adjust the volume of the Pro-ject to your liking. This should give you considerably more gain.

 

[david1rest]

many thanks for this fast answer.
 
additional question: is my electricity bill going through the roof, if i put the dac on max volume the full time like you adviced?
then its max. laptop + max. dac + half max amp?

 

[billybob_jcv]

FAR, FAR less than the power supply in your PC or the LCD monitor you are currently staring at!

 

[ProtegeManiac]

 
I then bought an relatively cheap amp (Pro-ject HeadBox S). Thought it would give my Sytem more Juice, but once i hooked it up to the DAC via the RCA cables
the sound was really quiet. I had to put the volume knobs up to 3 oclock, on BOTH machines, and my Laptop volume to a frickin 100 percent.

 

Does the Pro-ject have adequate power to drive the DT990 Pro? The spec I saw said that it has a gain of 11 and can put 60 millivolts into 300 ohms. 

 

From what I remember of the original Headbox in some other thread, it's basically a CMOY of some kind, and not even that much more powerful than the best 9v powered designs. The S might not be too different from that. For less than the price of the Headbox the Schiit Magni makes a lot more sense, unless you are integrating the Headbox into a speaker system built around a small integrated and the pass-through then becomes a crucial requirement.