Integrated preout to subwoofer is the best

My subwoofer (Sunfire Architectural),for the past 6 months, was hooked up via speaker cables from my YBA Integre. The YBA had the facility for biwiring, but no pre out. Now, my new YBA Passion Integre, has the preout capability, and from everyone I talked to (including YBA and Sunfire), this was the better way to go. Can anybody tell me why? Exactly what's going on here? The preout, to my sub, is significantly (prodigiously) better sounding. The interconnects are a short run of 4.5 feet. Thanks in advance.
The best for that subwoofer maybe; but if you had a REL sub you would probably come to different conclusion for audio. As always, "every system is different".
I had a sub at one point and when using interconnects it bypassed the hi-pass filter and wasn't recommended. Then again it was a rather inexpensive one.