Looking for multi-input, high-quality setup

[Tiazmat]

I am looking to make a setup to use my headphones with multiple inputs at the same time. I am looking for a solution similar to the Astro MixAmp, which I already have, but aren't nearly enough to power my Beyerdynamic DT 880's, which are 600 Ohms. I also have a Xonar STX, but I would be willing to sell it and get a different solution if there is something else favorable that is still able to power my cans.

 

What I'm mainly looking for:
1. Are there any other devices that accomplish the same thing as the MixAmp, but are more powerful?

2. Would it be reasonable to output from a Mixamp to a dedicated Amp or DAC/Amp combo?

[NannerBeans]

What specific inputs do you need?

[Tiazmat]

It needs to have a way to connect my PC to it (so something USB, RCA, or something else), and then RCA. Multiple RCAs would be nice but not completely necessary. Would also like a 3.5mm, but I could deal without one. I don't need digital inputs, unless that is the intended way to connect it to my PC.

[ShearMe]

It needs to have a way to connect my PC to it (so something USB, RCA, or something else), and then RCA. Multiple RCAs would be nice but not completely necessary. Would also like a 3.5mm, but I could deal without one. I don't need digital inputs, unless that is the intended way to connect it to my PC.

 

Have you considered an RCA switch or cheap mixer, and sending the output into your computer's line-in? That way you could make use of the soundcard you already have.