2x20mm2 or 1x35mm2?

2x20mm2 or 1x 35mm2 Hi people so far I had two bridge power stages, each with 20mm2. Now I have to climb to an Audison VRX 2,150 and an Eton Pa5402 now I would have to put thicker, but it would be enough to clamp both cables on a distributor and from there to control the amps??? The piece is maximum 30cm long, which cross section should I use to control the steps? Two caps should also be connected, makes A few suggestions! It wouldn’t be an issue in itself but the price is so horrendous! MfG