[rmurray]

 Going with the EQ idea in my case I assume it would would be best connected between my CD player and the preamp.

[Phil A]

Don't laugh.  When I had my separate parametric equalizer many moons ago and before I decided it would be best to just sell it, I installed it between a time delay unit (for surround sound long before there was Dolby) and an outboard amplifier.  Then I realized I was just crazy put a $500 (back then - like 35 years ago. when I was 8 years old of course ) equalizer in that chain and I sold it. Back then my biggest use for it was minimizing a particular narrow band for tape hiss.

[JLM]

Yep, I now use a DSPeaker (for DAC, preamp, and DSP) up to 250 Hz.  With my single driver speakers I only need two mono-blocks.  250 Hz was selected to reach the baffle step frequency of my speakers as the mono-blocks are wired directly to the drivers. 

Einstein said: "No more complicated than necessary," so the system consists of my laptop, 3m USB cable to the DSPeaker (that does have a dedicated power supply), 1m interconnects to the mono-blocks, 8ft speaker cables to the single driver speakers.  The room (my basement study) fits the Cardas Golden Cuboid proportions so treatments are 98% ineffective.  Duke LeJeune (thankfully) did talk me into adding Late Ceiling Splash ambience tweeters that parallel the speakers. But even my Ikea nightstand "rack" has been replaced by a 43" x 12" shelf that's spiked to the floor and sits 3ft from the front wall (opens up the soundstage, allows for shorter speaker cable, and allows for easy access).