I realize that the majority opinion on this forum is that the main strings provide the main feel and power of the stringbed. So, a hybrid of gut mains and poly crosses, for instance, would feel like a "stiff gut". And the reverse, having poly mains and gut crosses, would feel like a "soft poly." At least that's what people keep saying. I just wonder how many of those people have actually TRIED both hybrids, or are just repeating what other people have written before. However, my experience with gut and multifilament strings is that the crosses always break in first and often snap before the main strings are even broken in at all. You can tell with gut and multis because the fibers break apart and become cloudy rather than clear or translucent once the strings are broken in. My thought is that it would be impossible for the main strings to bear the brunt of the power if the crosses are the ones that are experiencing the most stress (judging by the condition of the strings). My theory is that the crosses are chiefly responsible for the power and the main strings are responsible for the spin, as it is the tendency of the main strings to deflect and slide over the cross strings when topspin is applied. So if the main strings are somewhat inelastic (like poly), they would deflect and rebound much quicker, applying more spin to the ball. But the main strings would not be responsible for the bulk of the power, unless they were at a dramatically higher tension than the crosses, perhaps as much as 10% or more. I guess a consequence of this is that I would agree that the mains should be strung noticeably TIGHTER than the crosses to provide a more evenly-balanced and uniformly-powered stringbed. That is because the crosses are experiencing the higher stress while the mains are too loose by comparison to actually experience enough stress to break them in. This makes sense also because the shorter cross strings, when deflecting an amount equal to the main strings, undergo a higher degree of strain. So, having more elastic cross strings (or otherwise stiffer main strings) makes more sense if you want a balanced stringbed and a larger sweetspot. I have also tried hybrids with natural gut mains and poly crosses. The natural gut mains hardly ever break in properly, while the poly goes dead much quicker. But I don't notice any real increase in power with gut mains. Fact is, an all-poly stringbed will have just about as much power as a stringbed with gut mains and poly crosses, strung at similar tensions. Aside from a slight increase in feel, I can't see any real benefit to having gut in the mains as compared to, say, a cheap synthetic gut. The REAL benefit seems to be in choosing the proper crosses. If I switch to a soft synthetic gut in the crosses (keeping the same natural gut mains), the stringbed is MUCH more powerful than with the poly crosses. But as I said, if I just go with a straight all-poly stringbed, the power is the same, but I lose some feel/feedback and gain some spin. I am curious if anyone has any personal feedback on a particular hybrid that they have tried "both ways", that is with the mains and crosses strung one way, and also reversed. But all of the observations that I have made so far lead me to the conclusion that, assuming equal tensions on mains and crosses, the crosses will provide the power and the mains will provide the spin and control (only by moderating the crosses).