[autumndreams]

I'm a musician, and I'm working on getting my at-home computer recording rig up to snuff.  I do a lot of work with virtual instruments, samplers and synths, and I like to be able to compose with headphones on.  When it comes time to mix, though, I have a set of KRK near-field powered monitors that I use.  
 
My computer will be using an E-mu 1212m PCIe soundcard, which has a pair of balanced outputs.
 
I would like to use the output from my computer to drive a headphone amp and my KRK monitors, either simultaneously or by using some sort of mechanism to switch between the two (headphones on/monitors off to headphones off/monitors on).
 
I'd like some input as far as what my best option would be in this situation.  The KRK's have balanced inputs, and the M3 has an unbalanced input (as far as I can tell) ...would I have any trouble using the balanced output from my computer to feed both the powered monitors and the headphone amp simultaneously?  Or would using a switch to route the signal to either the monitors or the headphones be a better idea?
 
Any input would be greatly appreciated.  I'm trying to work out all the kinks before I start working on building the amp.

 

[amb]

Quote:

... I would like to use the output from my computer to drive a headphone amp and my KRK monitors, either simultaneously or by using some sort of mechanism to switch between the two (headphones on/monitors off to headphones off/monitors on).

You could drive them both simultaneously, or switch between them.  It's up to you how you want to do it.
 
Quote:

I'd like some input as far as what my best option would be in this situation.  The KRK's have balanced inputs, and the M3 has an unbalanced input (as far as I can tell) ...would I have any trouble using the balanced output from my computer to feed both the powered monitors and the headphone amp simultaneously?  Or would using a switch to route the signal to either the monitors or the headphones be a better idea?

The M³ could be built into a fully-balanced amp using two boards, but it would require that you re-wire your headphones (see the "other options" section of the M³ website.
You could instead build a standard unbalanced M³, but insert a balaned-to-unbalanced converter at its input.  This could be a special transformer designed for this purpose, or a simple active circuit based on the THAT1206 or INA134 chip.
Lastly, you could simply ignore the cold signal from the sound card and use only the hot and ground wires on the interconnect.  This loses the CMRR benefit of balanced interconnection, but it requires no parts and is the simplest solution.

 

[autumndreams]

Thanks!  That's exactly the info I needed.
 
I head read up about the potential for running a balanced setup, but I'm not really excited about that possibility...I've got about three sets of cans that I use at any given time, and *really* wouldn't want to go about converting all three of them .
 
Can't wait to get started on this, it's been about two years since I've had an electronics project to tackle.