Subwoofer Isolation, what do you think...

I just got this big honking subwoofer, a DD-18 Velodyne. I've a ceramic tile over concrete floor. I also have a nice turntable in close proximity to the only WAF approved site for the big honker. Anyone have any feeling for if the adjustable feet that came with the DD-18 are enough or should I replace them with cones or something else? I always use the sub even with the vinyl as it adds so much depth to everything. I can't say my turntable's stand is very good, it isn't but I'm working on finding something good (and affordable!). I am concerned though with this big thing so close... maybe within four feet.
Thanks People!
Oh Yeah get a 25lb bag of #6 (I bought #7.5 instead because that is what the gun shop had in stock and it works also)lead shot and throw the bag on your sub with whatever isolation you choise it will tighen up the bass more by adding mass to the top of the sub cabinet. Especially with an 18" subwoofer cabinet!
Look into Sistrum stands for the subwoofer. It will isolate it beautifully and improve it sound.

I believe that you may have misinterpreted Newbee's post. He was not discussing whether to isolate or couple the subwoofer. He was suggesting that air-borne vibration was the major issue in Sailfishben's system and that he should attend to that at the turntable. Newbee also suggests that Sailfishben try decoupling the turntable so it is shielded from the vibration from the subwoofer. Maybe Newbee can clarify.

I would say that sending more of the subwoofer's vibration and energy into the floor through rigid coupling is not the best method to control that vibration because the vibration will travel through the floor towards the other equipment in the system and have negative sonic effects. If the other equipment is also rigidly coupled to the floor the vibration will have a direct path into the equipment through the supports. A rigid coupler (whether it be a point, a spike, a slab of stone or wood, etc.) does not have the ability to send vibration in only one direction (out of the component). By virtue of its rigidity it allows vibration to travel in BOTH directions - also up INTO the component.

Best Regards,

Barry Kohan

Disclaimer: I am a manufacturer of vibration control products.
WAF factors dictate putting a 25lb bag-o-shot on top of our beautiful piano gloss black BIG HONKER will only land me in the doghouse so thats out. This thing weighs in at 120lbs... it ain't moving. Hell, if it was only a bit bigger I could use it later when I go to the big room. Kidding aside it seems like you all are telling me to stabilize the turntable first with a good rack etc. Besides the Sistrum's who's got the best price to performance rack? I only need it to be about 25" high. I'd only hold the phono amp along with the turntable so the longer IC run was to the processor, is that how to do it? Seems like starting with a decent rack or stand at an affordable (cheap?) rate then later adding another product to it fits in with my budgetary restraints.
Thanks people!