Balance "add on" for my Desk top Stereo Amplifier Case - DROK TDA7297

Bought the DROK TDA7297 stereo amplifier for my old Mod B pi
Bloomin! amazing value for money and sound quality, IF have suitable 12V power supply and old speakers.

They are widely available on both Amazon and ebay here's one link:
http://www.ebay.com/sch/sis.html?_nkw=DROK+TDA7297+Mini+Digital+Amplifier+Stereo+Audio+Ampli+Electro+12+Volt+Amp+New&_trksid=p2047675.m4100

But they have two problems

1. No case
2. No balance control

Well created case, but its available else where (sorry need the cash)
https://www.3dagogo.com/3dagogo/designs/natkoAMPCASE

Now balance control is harder, the amplifier is a bridge type which for me means the output can not be easily altered (well on the cheep) .

So made this add on to provide balance control for my DROK TDA7297 case.
It's a lot more technical than just the case so decided to post it here.
The files create an add on case that takes the input and balances that in what I hope is a stylish manner.

The electrical explanation is here (see fig 9)
http://sound.westhost.com/pots.htm

I used the 100k Pot and 33k resisters as exampled, with a standard stereo male and female jack's available from local stores (one of each).
You will also need 2 off - 3mm by 10mm screws.

I hope to create an additional module that you could add additional inputs (bit like a mixer just add the module for each input you want)... but need to research if isolation required ???

Please note this is fiddly as hell wiring wise, definitely pre solder the wires onto the male jack before screwing in, as no space to solder once screwed in.

If you want to add feet they are 13mm inserts that will need levering out with small flat screw driver and the bottom thing needs a 3mm drill bit run down the holes.