The initial concept

Sparkfun.com is awesome.   They've got a large catalog of fun parts, but more importantly they have an incredible growing library of information for the beginner.  Arduino.cc is also awesome.   With these two (and, you know, the rest of the internet) I've been able to lay out a basic game plan

So here's the idea:

With the help of my brother, I found a neat part, the DS1807 2-channel digitally-controlled potentiometer.  This chip is controlled via I2C.  I will use five of these (one per channel and one on master) with an Arduino, controlled from the MythTV box via USB/serial.

Some LEDs for status would be nice.  These look perfect, little audio bar meters.  I'll need to learn how to control a lot of LEDs with not many pins (the arduino-loaded chip I plan to use has 14 digital pins and 6 analog).  A little research taught me about shift registers, where two pins become eight.  a google search for 'LED matrix' brings up a whole mess of ideas and info.

A knob + switches for a simple external interface would be nice.  Something like this and these.

For the microprocessor, I considered getting a full arduino board but ultimately took a leap of faith and ordered just the bare chip, pre-loaded with arduino bootloader.  This means I will have to lay out all of the supporting components myself (power supply, oscillator, etc) but it will also give me a lot more flexibility in my final design.

Finally, I came across the MSGEQ7, a neat little chip that could allow me to show a simple 7-band frequency display.