volume/chat mixer for PC headsets

hey everyone... i have an issue here i think i can fix with a small electronics project... i use headsets for my primary source of audio, and to chat when i play games... i have a surround sound processor that uses dolby headphone technology to turn a set of stereo headphones into surround sound... however, im looking for independant control of the chat voice and game volumes on a console

heres my idea.. i build a small box that i plug the two 3.5mm jacks into (one for the stereo speakers, the other for the microphone) and a USB plugin for passthrough of USB power

on the other side is a USB cable and 3.5mm stereo plug that goes to the processor for the surround sound audio and power

also on this box would be a 2.5mm stereo jack that a headset would plug into

the way this would work is the poles for the microphone would be soldered directly together between the 3.5mm jack that the headset plugs into and the 2.5mm jack that would plug into the consoles headset jack. the surround sound audio coming in from the processor would have a volume control on it, maybe some sort of slider or mini potentiometer to control the game volume

the audio coming from the 2.5mm headset jack would be soldered to another volume control... and post-volume control, both the game audio and chat audio would be soldered to the 3.5mm jack leading to the headset... this would allow me to adjust game and chat volume independantly so game volume will not overpower voice chat

i know exactly how to wire this all up, and i can get a small project box from an electronics part store... my question is for this application is what should i use for the volume controls on a project this size?... to adjust volume on a PC headset?.. i need a volume control small enough so the overall size of the project will be compact as possible.. also.. 25k, 50k? which size would i be needing for this project?

and lastly... how would i go about adding a USB powered amplifier to a project of this size?

A volume control usually adjusts the input level of the amplifier that feeds the headphones but some high impedance headphones have a volume control built-in.

You forgot to tell us the impedance of each earphone for us to select a volume control value to connect to it. It might be 25 ohms or 100 ohms, not 25k ohms.

im looking for something general purpose that i could plug a variety of PC headsets into, im not looking at any particular model and sometime later im thinking of making my own headset entirely using a thick gage wire for the shape and structure of the band and possibly some hollowed out wooden, or possibly even carbon fiber ear cups, but thats much later on...

anyway, most common PC headsets have an impedance of 32 ohms up to 50 ohms... so between 32 and 50