Belles 21A specs

I'm looking for the product manual (or spec sheet) for a Belles 21A. I contacted David earlier today, but thought I would ask here.

Mainly, I want to know the input and output impedance. It sounds great using 2 meter XLR cables into my Sunfire amp, but I'm thinking about rearranging components and will need a 7.5 meter length. I don't think the Belles is a truly balanced design, so I'm worried this might not be an ideal situation. Of course, I can try and find out, but that means buying cables. FWIW, the Sunfire has an input impedance of 20k. Any thoughts/advice welcome.

Thank you!
Dave sent the product manual (blessings to him), but the output impedance isn't listed. I guess I won't worry about it. I'll just move forward with long ICs and see how it sounds.