It says on Xtant's website that the 6.1 (600wrms into 2ohms) has a lowpass crossover (20-120Hz) and also passthrough RCAs to send the input signal to other amps (such as frontstage amp for components). My question is, does this mean that I can send the input signal to the Xtant 6.1 and set my crossover freq. and the rest of the signal will be sent to the frontstage amp?
No. If you use the non-fader signal to the xtant, you will only have a non-fader signal that will come out of the amp to hook up other amps for bass. If you want a frontstage signal, you have to send the fronstage amp the signal from the front speaker rcas. Also, if you set your crossover on the xtant, it won't mess with the signal coming out of it to other amps. But you don't want the signal going to your fronts if it is a nonfader signal. I think that's what you're saying. I, of course, could be totally wrong.
I only have L+R RCA preouts on my HU which send the full signal. So basically I wanted all low frequencies (eg. below 120Hz) to be amplified by the Xtant 6.1 and all the frequencies above 120Hz to be amplified by the frontstage amp.
However from what I gather from your post, the signal that comes out of the xtant 6.1 is the fullrange signal (including frequencies below 120Hz) which I don't want going to my frontstage amp. Therefore, the only solution I can think of is an external highpass crossover at the output RCAs of the Xtant 6.1 which sends only the part of signal above 120Hz to the frontstage amp.
Do you have any suggestions on another way that I can achieve my goal?
If you only have 1 pair of RCA preouts then yes, the only thing you can do to get rid of the lower frequencies is with a crossover. The signal out from the Xtant 6.1 is a full range signal. Whatever amp you hook it up to though should have a high pass filter or some kind of built in crossover. What amp are you going to use for your frontstage? Also, a crossover would be connected to your speaker wire, no to the RCAs. It sounds like you may not know if your frontstage amp has a high pass filter. What about your deck? What kind is it?
Man, I sure wasn't thinking straight when I typed those posts. My Zapco Ref350.2 has a fully variable electronic crossover so I guess there was no problem in the first place. Thanks for your help anyway James.