connect sub woofer from preamp out on integrated?

A newbiew question. I would like to enhance bass to my 2 channel system by adding a sub woofer via Preamp out from my integrated. Is there any problem with that?
No. Depending on the bass capability of your main speakers you might consider using bass management -- either built into the sub or via an external controller. Let us know what other components are in your system and suggestions can be made.
Thank you Bob. I have a Classe CAP 101 integrated amp with preamp out and an Epos sub woofer. I also have a pair of Gallo micro Ti speakers that don't do the low frequencies. Wanted to make sure I can't damage any components by feeding sub from preamp out. In the past I have connected the sub to a home theatre receiver that has a dedicated sub woofer single cable output. The Classe has a 2 channel preamp output, of course---is only one cable required to drive the mono sub or should I connect both preamp outputs to sub? Much obliged for assistance.
There should be no problem connecting the preamp outs to the subwoofer. You should connect both left & right preamp outs to the sub. It will sum them internally to form a mono signal.

When you say the Gallo micro Ti speakers don't do the low frequencies, how are you preventing the bass from getting to them? Aren't you running them full range?

If the CAP 101 has amp in jacks, as well as, preamp out, you should seriously consider bass management. Your main speakers are very small.
yes, I am running the Gallo speakers full range....plse explain what bass management means.....thx.....
The concept of bass management is to route the bass frequencies to the speaker(s) that are capable of producing bass. It's what AV receivers (and pre/pros) are doing when you specify that you have a sub connected and the main speakers are "small." Saying the main speakers are small will insert a high pass filter in front of the main speakers effectively blocking the bass frequencies from reaching them. Saying that a sub is connected will cause the bass frequencies in the front channels to be routed to the sub.

Bass management is very important for small main speakers like yours. According to the Gallo web site, your speakers have a frequency response down to 120 Hz. With speakers this small, the subwoofer will operate in a region where it could be localized. Ideally, you shouldn't be able to hear the subwoofer; only once turned off should you realize that it was playing before.

Two channel bass management built into preamps or integrated amps is very rare. A few two-channel receivers provide it. There are 2-channel bass management controllers available -- one is the NHT X2 filter. But, to utilize it with an integrated amp, the amp has to provide both preamp out jacks and amp in jacks; basically you need to be able to treat the integrated as separates in one box.

Also, there are some subwoofers that provide 2-channel bass management built into their plate amps.

Hope this helps.
Indeed, that is very helpful. My Epos sub has hi and low level inputs/outputs (with a variable frequency cut off filter) and I think I am starting to understand what needs to be done....unfortunately, the Classe CAP 101 has pre amp out, but no Amp IN jacks....could I use the Tape IN jack instead of an Amp IN? Thank you for your patient guidance.
I think you're just out of luck in doing bass management. Keeping the volume low will lessen the distortion produced by your main speakers. If there's not much bass in the source material you listen to that'll help.

You might consider running stereo subs since the subs will operate up to 120 Hz. In this situation, you'd run the left preamp out to the left sub (placed pretty close to the left speaker) and run the right preamp out to the right sub (placed pretty close to the right speaker).

You didn't say which Epos sub you have, but with your speakers it would be better for it to have a smallish driver, maybe 8" instead of 12", so that it would be more like a woofer than a subwoofer.

You might also contact Gallo and ask if the speaker is band limited in the bass. It'd be nice if it was.
Thx again for providing thid info. I probably need to re-think this system. Fortunately it is a second one.
I'm doing the same thing. Do I just need "normal" RCA-type cables?
I'm connecting a Vel' Optimum-10 using the preamp outs from my Cambridge Audio Azur 840A II. They look like normal RCA outs. Or, is there some sub-specific cable interconnect I should be using? Advice? Thanks in advance!
Oh.. My mains are Heresy III's, not sure if it matters. If anyone has similar experience, I'd love to hear starting points for x-over, et. al.