Thought this might interest you OB guys, this looks really interesting:

We are proud to announce the release of the PAP-C1, a two way Active Analog Crossover, designed by Nelson Pass and FirstWatt for Open Baffle and PureAudioProject.

The PAP-C1 was specifically designed for speakers with woofers and full range drivers, a popular and raved configuration in PureAudioProject offering.

Based on FirstWatt legendary B5 crossover, the PAP-C1 revised JFet filters allow smooth  -12db low and high pass filtering between 100hz to 550hz

In addition, the PAP-C1 features adjustable low-bass boost and a gentle high-mid notch on board, and a continuous gain adjustment of the low frequencies on it's front panel, aka 'loudness'.

PureAudioProject unique modular offering features a variety of full range drivers and their matched passive crossovers integrated with 10" or 15" OB woofers in Open Baffle speakers. With Nelson Pass / FirstWatt revised design, the PAP-C1 offers such flexibility also for bi-amping and active crossovers fans, while keeping the entire audio path pure analog and audiophile.

Papa Pass is an aficionado of full-range, single driver speakers.  If you checkout some of his forum posts, white papers, blogs, etc. you can find specific examples of some of his favs and homebrews.  A couple of his FirstWatt amps, while not being designed specifically for the typical impedance/frequency responses of these types of drivers, are quite complimentary to them – current source amps.  He has a couple of white papers on CS amps that I can point you to if you’re interested.  They are available on the FirstWatt website - http://www.firstwatt.com/pdf/art_cs_amps.pdf    They make for quite interesting reading.  He believes that CS amps attain higher fidelity when paired with appropriate types of speakers that also have a “current source crossover filter” – these also detailed in one of his white papers.  
In an email exchange I had with him not long ago, he stated that he actually voices his amps with Lowther PM6A’s and a pair of big vintage Tannoys.  And the most recent FirstWatt amps he recommended to me for driving single driver – full rangers are the J2 and F6.  The F1 was also a power trans-conductance amplifier (or power current source, if you like), but is no longer in production.  It has been my experience that anything Nelson Pass puts his name on, or is associated with, is very, very good sounding kit – just like Decware.  Nelson Pass is also one of the most gracious engineers/designers in all of high-end audio.  He will help you trouble shoot your DIY amp as well as sharing his own circuit designs.

Yes, the price of that unit makes it apprehensive to a lot of us.  Considering you can get a miniDSP for under $300 ~ though the 1st Watt keeps it all analog which is pretty cool for us vinyl guys.  Like Decware's stuff, the PAP-C1 looks to be of that built like a tank quality as well.

Ashly makes an "analog" electronic xover.  Do not discount Ashly Audio, just because they are a "Pro" oriented company.  They make some mighty good sounding products and have been in business for decades.  
Don't forget fellow "philes" most of the music we listen to passed thru "pro" audio equipment when it was made and recorded before it ever got to us.

I have used the Ashly XR-1001 xover to good effect on many an occasion as a low pass to subs/bass units.  If it has any negative effect on the signal passing thru it - it is d...n small !!!!!
You can typically find these brand new in the box for about $199.  I had one long ago for many years.  Finally after several years of not using it, I sold it.  A couple years later, had a need for it again - bought another one.  I won't make the mistake of selling this one.  I used it most recently to low pass to my Augie amp... before I picked up a Crown XLS (with built-in xover) to drive the Augie's.  Ashly has updated the circuitry in this xover over the years, but has not changed the product name/number.  The one I have now, is a couple years old, but is a different and better unit than the original one I had.  Check it out if you need an electronic xover - especially if you need one for low-passing to subs.  I think you might find it more than adequate - and the price is right.