Adjust frequencies of a 2.0 setup

Good evening, I have a 2.0 setup and would like to find some way, some kind of application/software, to help me fine-tune the audio frequencies of the Audyssey calibration.

I've been researching and only found the famous REW and the OCA A1 threads, but I can't use them because the only way to utilize the OCA process is with a subwoofer in the system, and I'd like to work on the frequencies of my Polk front speakers while I still don't have a subwoofer.

If anyone knows a way to adjust the frequencies of a 2.0 setup, other than the Denon Multeq app, I'd be grateful. Thanks.