  The cutoff rate $R_0(W)$ of a discrete memoryless channel (DMC) $W$ is often
used as a figure of merit, alongside the channel capacity $C(W)$. Given a
channel $W$ consisting of two possibly correlated subchannels $W_1$, $W_2$, the
capacity function always satisfies $C(W_1)+C(W_2) \le C(W)$, while there are
examples for which $R_0(W_1)+R_0(W_2) > R_0(W)$. This fact that cutoff rate can
be ``created'' by channel splitting was noticed by Massey in his study of an
optical modulation system modeled as a $M$'ary erasure channel. This paper
demonstrates that similar gains in cutoff rate can be achieved for general
DMC's by methods of channel combining and splitting. Relation of the proposed
method to Pinsker's early work on cutoff rate improvement and to Imai-Hirakawa
multi-level coding are also discussed.
