preamp with only 1 set of pre-outs: adding sub....

My pre has only 1 set of pre-outs which are being used by my does one hook up a sub with this dilemna? Am i going to sacrifice bass accuracy to make this work?
Depends on the sub. Some have built-in HP filters for your main speaker/amp.

A pair y connectors will allow you to connect both to the outputs. Not a purist arrangement but works fine and I doubt anyone can hear the difference.
I connect my sub using high level inputs connected to my power amps. I find it far better. But if you want to use pre-outs, the y connector is the way to go.
ACI Speaker Level Converters (scroll down the page)...these connect to your amp's speaker outputs. They work great.
I have a powered sub. I ran my pre-outs from the pre-amp to the high pass filter on the sub and from the outputs on the sub back to my amp and ran my speakers from my amp, using the crossover on my sub.
As Kal and Sprink have stated, unless your main speakers are full range you'll probably be happier taking the bass load off of them by using a high pass filter either in the sub itself or an external bass management controller.
Like Bdgregory pointed out, you can connect the sub taking the signal from the speaker posts on you amp and connect speaker wire to "the speaker in" input on your sub (Not all subs have this connection). You would leave your speakers connected as usual to the amp, and this has no impact on the load that the amp sees.
Some argue that this is the prefered method of connecting sub (REL subs being one advocate and fitting their subs with speakon high level inputs), whereas others disagree. There are some threads on that topic here on Audiogon if you are interested.