Sub Connection Help

Can anyone help? How is it possible to have a smooth transition from sub to main speakers without using an active crossover?
I have JMLab Mini Utopia and I plan to add a sub ,but before I do so I would like some help concerning set up alternatives,since there is no active crossover in the hi-fi chain

hey. i just bought a vandersteen 2wq (it's got a built in 300watt amp) and only cost $1,300. (only! know what i mean). this sub was supposed to work wonders for my electrostatic speakers (acoustat model IIIs) and it did! ive since learned that lots of people with electrostats love these subs. the crossover is a passive one. it's a simple plug that connects into the end of the preamp interconnect and then that goes into your amp. i think it made a huge difference to the sound. i love it. LOVE it! i hope that helps answer your question. go to audioasylum and post your question there or do a search and you're bound to come up with the answers as well.
good luck
REL Storm 3--truly easy to set up /for most any application/ also musical for ht or 2ch.
I also recommend you check out the REL subs. The verson III of most models have controls to fine tune the crossover in 2Hz increments. Very easy to set up and integrate.
Definitely a REL. The ABC(?) connection taps into your amp output so it gets the same signal as your speakers but it does not present a load to your amp. Combine that with crossover adjustments of 2Hz to intregrate your speakers. Call Sumiko or e-mail them with any questions regarding which REL sub for your system and placement issues, they are very helpful.