Do bear in mind how cheap a 2x4 HD is in the context of the rest of your system - it is a very good value unit but higher performance options exist.I started using room correction recently- MiniDSP HD, originally I hoped to cut off woofers in my speakers fairly high - around 100-120Hz to relieve my amplifier from all hard work but I wasn’t very impressed with the changes it made to the sound . In the end I’ve tried running pre out into amp section through DSP with everything bypassed, conclusion was A/D and D/A conversion definitely does something to the sound which I wasn’t very keen on . In the end I decided to use another pre out going to DSP to correct and fill bottom end below 60Hz without cutting off woofer ,sounds much better but I’m still experimenting as SVS subwoofer has its own equalisation which I use to bump lows before applying DSP. Still long way to go but it’s early results are promising .
Good to see you're making progress re. the sub .