In our last sound for video session we covered high pass filters. One thing I showed was that applying a high pass filter can mess with your waveform's symmetry, essentially robbing you of headroom. Then I showed that the RX5 high pass filter, didn't see to have that effect.
It turns out that RX's digital high pass is what is called a "Linear Phase EQ" which means that it is generally won't change the phase of your waveform when applying a high pass. That's a good thing.
But Izotope RX is a pretty expensive piece of software and not all of us can afford that. As an alternative, I just received an email from WAVES, makers of audio plugins, with a deal today on a linear phase EQ (which includes a high pass filter) and a linear phase multiband compressor for $69. The normal pricing for these two is about $300 USD. WAVES makes quality plugins so if you are in the market, this is probably worth a look.