The idea would be to use the RCA output from my dac, connect it to the eq, connect the rca output from eq to my headphone amplifier (A-100).Depends if you mean analog in/ analog out, or analog all the way through. If the former, you can get PEQ, which is best, in something like MiniDSP 2X4 or MiniDSP 2X4HD. If you want totally analog, maybe a vintage graphic equalizer, which will have a high noise floor, or perhaps wait for the one Schiit plans to release this year.