Does sub cable also have to be high end?

You know bass is the single most difficult thing to get right in any domestic room environment! Things such as getting flat frequency response and basic sub/main speaker integration is far more important than ANY cable consideration for a subwoofer (dedicated bass)!!!
I'd only consider playing with different sub cables, well after you got the sub placed, dialed in, and/or EQ'd properly for the seating arrangement!
On an overall scale of importance, I'd rate interconnect cable importance for a bass woofer a "1" or "2"(at best) out of "10" on the scale of relative importance.
Yes, cables do make sonic differnces/improvments/degredations/etc. However, I'd start with some basic tried and true Monster cable THX sub cable or something. I think you'd be just fine! Again, most people would do well just to get the darn woofer dialed in properly! Most people have the sub way too high! booming the room and bloating the bass over the midrange! (result...one notey bass!)
Also, however, for the record, another basic affordable interconnect for bass woofers is the Straight wire Miestro! This is excellent bass response from copper! It's tight and extended. If you want to play around with some silver interconnects, you'll find that the bass note tightens up a bit. However, this is most noteable, again, after proper woofer set up!
So, my recommendations for you is probably either MOnster THX or something, Straight Wire Maestro, ETc..Or, just some copper subwoofer cable for now. You can try cable wars after you get the set up process down!

Have not tried a new sub cable yet, but I found a big improvment replacing the stock power cord on my REL.

Hello Lornecherry. I bought the DH Labs BL-1 sub cable after checking with Wen-Li at AudioNet, and Robert Stein at the Cable Company. Like yourself I didn't feel the need to go overbord with a sub cable, but felt that some attention was necessary. No offense to those users of Monster Cable interconnects, but they can't hold their own when compared to many other affordable brands. Of, course they are usually better than stock cables. I have fairly high end cabling, and was worried that the DH-Labs wouldn't be enough, but those dealers assured me it would be fine, and they were right. XLO is known for making a very good sub cable as well, so perhaps you can start there, and compare the two on your sub. I got a more defined pitch and a tighter, slammier bass. Sugarbrie is right about replacing the stock power cord. You don't have to spend a lot. There are 3 or 4 reasonably priced ($40- $150) power cords that will do a great job, and make a significant difference. Good luck.

I'm using subwoofer cables from BetterCables and am very pleased with their build quality and performance. They can be purchased in varying lengths (each of mine are 3 meters), and they sell for $30-40 each. Check out their Web site: www.bettercables.com

without any hesitation go directly to xlo cable for sub

Thanks Bmpnyc. I saw the BL-1 subwoofer cable at an audio site, but forgot where. Audionet you say? I was wondering how it performed. Glad to hear it's working well in your system. For the last six months I too have been getting good results with DH Labs cables for bass. I have DH Labs Silver Pulse interconnect hooked to my sub. I think it has excellent tone and extension. Very tight.

For hand-soldered and terminated DH Labs cables, call Jeff at Value Audio (831-464-3864). He hand-made some BL-1 cables for me in different lengths and did a beautiful job. Plus prices are great.

Try comparing Sc53's suggestion and Wen-Li at: eAudioNet.com

Sub cables absolutely will make a difference. Does your bass performance improve when you use better speaker wire and/or interconnects? Then, why wouldn't your sub?

A pair of XLO Reference 2 1a interlinks and a Wireworld Aurora III powercord made my Sonus Faber Gravis subwoofer sound much better than it already did......