Amplifier Woes!!

Hi People, I am using a Kenwood 7016 HU with Infinity kappa 65.9cs comps in the front. Id been looking to buy an amplifier to power these kappa's and have tried Focal Solid 4, Kicker ex450.4 , JBL GTO 1004. (which I already have) All these 3 amplifiers and very different sound signatures. To elaborate little vaguely. 1. Focal solid 4: Is giving a very balanced sound (Gives me better control for EQ settings but I feel absence of many background tones) 2. Kicker: MID range is more prominent. 3. JBL: High frequencies are little prominent but overall presence of tones is way clear then FOCAL or KICKER. The JBL GTO is rated at 150 watts x 4 channel at 2 ohms whereas the Kappa's are rated at 90 watts. I want to understand that is it safe to install the JBL amp with Kappa and if yes then how should I set the gains of the AMP as they start from 6.5 and increasing them to 4V to match my HU increases the output way too much though it does not distort.:Frustrati PS: I do have Gaps in my understanding of ICE.

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