Adding a subwoofer to a system question

Wasnt sure if I should post this here or in the Misc. Section, but figured I would get more answers here.

Here is my question : If a subwoofer such as the Sunfire True Subwoofer Super Jr. ( using this for example ), is added to the system, is a Preamp needed IF the CD Player that is used has volume control ?

Here is another question regarding that....I have a pair of Klipsch Forte 11's which dont require a lot of power to play loud, so could a inexpensive tube amp be bought such as a 2a3 tube amp ( or any low power tube amp for that matter ) that has nice mids / highs but doesnt have the low end be used and that is where the sub would come in the picture ?

Advantages / Disadvantages ?
Here's a low-cost but very good performing solution.
Get a Paradigm X-30 crossover (about $100-125 used here when they show up). Run your volume controlled CD player into the X-30 and the outputS (now 2 for sub and amp to speakers) from the appropriate outputs on the x-over. You will then be set!

An even cheaper way would be to split the signal from the CD player using a simple line-splitter (radio shack has them)
but with that, both the sub AND your amp would be seeing a full-range signal. The X-30 is a NO brainer!

Also, 2a3 amps usually cost MORE then a KT88 or EL34 amp and have low watts (usually 1.5) I don't know the sensitivity of the Forte 11's, but they'd need to be close to 99db for a 2a3 amp. If looking for the SET sound, consider an 8w 300b amp. But if looking for a lower cost route, try an EL34 or KT88 amp.
Good Luck and Good Listening!
Myraj hit it perfectly!
Since bass is so power hungry, a sub with a nice crossover will take all of the strain of reproducing low bass away from the tube amp and you will get much more bang for your buck. ie 6 watts to drive everything above 80hz and 250 watts for the bass?
Yes an active external line level crossover is the solution for adding a subwoofer. Either NHT's X2, Hsu Research or Paradigm's X30 should all work well. I'd suggest going Hsu for both sub and crossover.

If you think you have to have tubes, consider the little Decware Zen.
Thank you for your input on this.