Preamp for 3.1 Channels with Bypass Switch

Hi all,
Given that this is my first post here I appreciate all opinions :)

I started designing my own 3.1 preamp because I did not find a simple, solid and expandable design anywhere. By simple I mean few parts and by solid I mean low THD and noise.
By expandable I mean usable as a stereo mixer in the future, by adding a virtual ground and an inverting opamp or adding more pots for variable filters.

The inputs are designed to be fed mainly from x.1 PC soundcard.

My main concerns before actual building the prototype are the auto oscillation of the opamps and the unforeseen issues I may have overlook :) Nobody is perfect.

I started looking first at simplest designs such as this http://www.dianziaihaozhe.com/yinxiang/407/ and this http://www.circuitstoday.com/subwoofer-amplifier but I did not want to compromise neither the quality or the simplicity.