Does anyone make a preamp with a subwoofer output?

This should do just what you want:
https://6moons.com/audioreview_articles/passivepreamp2/
This is the review of the Icon4 PRO which allows you to use high and low pass filters for your mains and subs. The reviewer is a bit loquacious (wordy) but he had the same problem as you and found this to be the best solution.

Here is the site for Icon:
https://www.passivepreamp.com/
The Icon4 PRO is only mentioned at the bottom of the site as coming soon. 

All the best,
Nonoise

The best and most cohesive way to connect your subwoofer is using high level outputs from your main amp. I have tried line level and speaker level many times and have always found tapping off the amp to be the most natural sounding of the two options.

Oz

ozzy62,

I have Acoustat Model X speakers that come with their own Servo amps that have three wires going to the speakers, not two, so I can’t take the high road.

Thanks

JD

nonoise,

 Is this what you’re talking about?
http://hifiknights.com/reviews/preamplifiers/icon-4pro/

You we’re right, the author of the 6Moons review rambled a bit.

Thanks.

JD

Thanks to everyone who replied,

My house was broken into the other day and getting some damage repaired has taken way to much of my time!
JD