Upgrade for old Dahlquist DQ LP1 Crossover

They still bring top dollar today. Very desirable due to it's flexability. I would keep it.

Are there any mods or tweaks that could be done to the DQ LP1 if I decide to keep it?

At one time when I was into the subwoofer thing I was using a LP1 modified by a local technician who upgraded all the capacitors and resistors. The improvement was clearly audible with less veiling and more transparity across the frequency spectrum. I sold the unit to a friend who used it for awhile until a speaker change put it in the closet where it still resides to this day.

So, if you're thinking of mod-ing it, by all means, do so. The results were worth the cost for me.

I upgraded the caps and resistors in mine and changed all of the jacks. The most important components in this crossover are the caps used on the passive side. These caps are in the signal path of the main speakers and need to be polyprop or polystyrene. Do not, under any circumstances, use the dipped silver mica caps that come with the unit. They sound terrible.