Your problem with the Motorolla cable box and Marantz are likely related. Both use "unusual" carrier frequencies. The CFL and plasma friendly receivers work by limiting the frequencies they respond to, on the CFL friendly receivers, the rejection band is adjustable, on the plasma friendly ones its not. The other popular brand that has a PITA carrier freq is RCA. Using the amplified connecting block helps because it raises the level of the IR that the receiver tries to reject, this solution doesn't work that reliably. The MAC1 is likely to be a very good solution, you will only be sending a single IR carrier to the infrared receivers, if it works well...it should be very repeatable. It can be difficult to use a CFL friendly unit w/ Marantz equipment. The carrier freq for most Marantz gear is 35 or 36kHz (helpful when setting up a CFL friendly receiver), for comparison Sony & Pioneer are 40kHz (typically) and RCA is 28kHz.

jcmitch