amp for interiors

Hey everyone. I've been doing subs, and boxes for a long time, but I have never used an amp to power interior speakers. I have a question about it. I just took my cousins old 100x4 amp (Jensen XA 4100) amp off his hands for 10 bucks. The problem is, He didnt have the High level input plugs that most amps come with. I was curious if its at all possible to use the low-pass inputs, and just switch the crossover on the amp, to Hi pass. I believe it should work, since the head unit I have has a single (rear, not sub) output. Any info on this would be great. thanks a bunch guys.

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1990 Honda Civic HB:
Clarion DXZ545MP H.U.
2- 6.5" Power Acoustik interiors
Diamond Audio 600.1 amp
Diamond Audio 15" M6MKII
Pyramid PB881X 4 CH. Amp

When you say high level I'm asuuming you mean one of the plugs that you just attach the speaker wires from you head unit to and it plugs into the amp. These are mostly just for someone who doesn't have pre outs (RCA's) on their head unit. The low level (RCA) inputs are just low voltage, low amperage signal channels. Since you only have one set of pre amp outs on your head unit just daisy chain (use the RCA out as your signal source) the 4 channel off of your sub amp, connect your speakers, switch the filter to high pass, and adjust your crossover and gain levels. You should be in buisness at this point

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If quiters never win, and winners never quit, who the heck came up with the idea that you should quit while your ahead?

thanks man. thats what i thought, i just wanted to make sure.

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1990 Honda Civic HB:
Clarion DXZ545MP H.U.
2- 6.5" Power Acoustik interiors
Diamond Audio 600.1 amp
Diamond Audio 15" M6MKII
Pyramid PB881X 4 CH. Amp