Here is an idea....just that so take it for what it's worth. Instead of making another similar product to Jolida's, how about making something like I am making for myself. The idea is this...
6 source input switch to buffer to 3 output switch, no volume control in this box. The idea being you can add this to any preamp or tube amp with volume pot you want to gain additional features not in the preamp/amp. The buffer is for impedance correction and IC driver. I think I may hard wire one set of output IC's to this box to rid of one less connector and keep it really short to go right under my preamp.
There are lots of cool preamps out on the market that just don't have enough features, but with something like this it wouldn't preclude that preamp anymore. 6 sources is probably enough for most but you could always add more. The 3 outputs are for tape/cdr output, external headphone output and preamp output. You can go fancy and make the selector relay driven so that it could be fully remote controlled. You can also add 3 on/off switches instead of output selector with independent buffers to make all the outputs independent of one another. It is a very simple concept, moderately simple to build and then allows the preamp to put all its resources into the circuitry and volume control.
The reason I wouldn't put the volume in the selector is two fold. First is simplicity and secondly it would be better off IMO in the preamp where the correct impedance of the pot can be determined and the appropriate type of VC can be made for the preamp in question. The headphone/record out don't need volume control anyway.
Anyway, this is an idea that I am working with. I just built my first tube preamp and for simplicity of build and to not commit too much $$ to an idea that I wasn't sure was going to work I decided on one input, one output. I am going to build this selector for myself to couple with it. Now I can play around with building different preamp circuits without having to bother with the inputs/outputs for the most part. If you want a processor bypass in your preamp you just add another pair of inputs with a switch that bypasses the VC. You can also add two pairs of outputs to your preamp as you want. There is more room for inputs/outputs and it is much easier to customize a selector than a preamp for layout reasons.
