No. This fear may have roots in observations that splitting a cable TV signal can add noise to the picture, or that plugging two sets of headphones into a portable player can reduce output to each set, however, neither of these has the same impedance relationship as line-level audio, which lends itself well to splitting. In fact, the only difference here with preamps that already have parallel outputs of the same type is that the Y-splitting is done outside instead of inside.