Downward facing subwoofer on carpet, bad idea?

I want to purchase the Paradigm PS 12 v4 Sub. Bad idea to put on carpet? What will be my loses in sound quality and what remedies (if any) are suggested?
I have Snell K Type/II Speakers, Mac MA6100 Amp.

IMHO, most all sub's are placed on carpeted floors, and most are downward firing. You don't lose low frequencies reflecting off carpet - only high frequencies - so there should be no problem at all. My Rel sub is on carpet and fires down . . . sounds wonderful.

It's not a bad idea, but it's not optimum. Place a solid surface, like plywood or a large floor tile, under your sub and compare. More of the sub's output will be reflected into the room by the hard surface verses some of it being absorbed by the carpet and padding.

My 2 RELs are also on carpet and work better in my room than my 4 12" each bipolar subs. I use cones under the rubber feet of the subs; may or may not improve sound for you. I checked with Sumiko some time ago about whether carpet was better; the person I talked with said bare floor but the technical person who later emailed me said carpet.
Good idea. Carpet and pad are pretty much transparent at bass wave lengths (a 11' long 100 Hz wave won't be phased by 1/2" of carpet and pad) but might do a little for distortion products and extra noises.
I tried my REL sub both ways, over carpet and next stting on a large tile, the carpet is my preference. It's easy enough to check yourself to see/hear which works best for you.
Shag carpet has a tendency to absorb more due to longer fibers...but the results are minimal...
I am very appreciative of your input to this question. Thank-you. Please permit me a new question. My amp
(McIntosh MA 6100) has jumpers in the rear which connect the "filter amplifier output (PREAMP OUT) and the power amplifier input (AMP IN). One source advised me to replace the jumpers with a "Y" cables and connect that to the sub. Another said to connect the sub to the left and right remote speakers terminals of my amp. Could you comment please.
First off your Snell K2's are awesome sounding 2 ways. Detailed, wide soundstage, speedy, dynamic and well controlled tight bass. Back in the mid 90's I sooo wanted to purchse them, but was putting the ex through college and....
So onto the amp. You have a few options to play with and everything being system dependent I would try them all and find which way you like. You can run a second set of speaker wire from the Main Speaker Out to the Speaker Level In on the sub, and then try from the remote speaker outs. Using the Main Speaker Out will give you the same signal the K2's see. You can also use a speaker to line level RCA converter (not expensive and can be found from car audio dealers)and try the line level input on the sub. Or just try the Pre Out and judge for yourself. If you decide to go with a line level input I would seriously recommend a Dspeaker Antimode 8033c. I use the "s" version with my two subs and have the best bass I've ever had. Dspeaker also makes a summing cable that you can run from your main speaker outs and converts to and RCA end to fit the Antimode.
As for carpet vs solid floor that all depends on the sub and the kind of bass you like. I've had a number of subs over the last 25yrs and some were better forward facing some better down facing on hardwood and some better facing carpet. As noted it is all system and listener dependent.

Hope this helps and Good luck