I think we are talking about three different things here.
First one, as I said it looks like a cross talk between VCO output, and VCA output. Microbrute do has a bit of it for sure (as many analogs), but it should be an issue. If it's too loud, maybe a ribbon cable inside is not in a proper position. We can check this if you want.
The second one:
I can play tones with Resonance Max and amount and rate of lfo
I'm not sure I really understood this, but a VCA has an attenuation, often around -70dB, it does not perfectly close when gate is Off. So if the filter is self oscillating very hard, the signal is very hot it's not surprising you can hear it a bit at the output.
See this post: http://www.arturia.com/evolution/smf/index.php?topic=14605.0
As I replied to the post, HP filter does not close totally when cutoff is maxed. Only LP closes.
It's by design. Same on minibrute.
Finally, it's not an excuse for everything of course, but keep in mind the price you paid, compared to the available features. With this ratio, it very difficult to match quietness of a very high end synth.