I guess it would look nice to get two of the SLD-44 since it is 8 channels. The cool thing about the SLD-44 is that each channel 1-8 would be adjustable via the pots on the top of the unit. I was confused at first but it adjusts it each separate channel. Luckily I had a DMM and made sure that each one was the same voltage (had mine at 8 ) and then it blended really well.
The thing that was different with the AudioControl Matrix 6 channel line driver is that the pot that was on top adjusted both channels instead of individual so it was easy to adjust and less frustrating to fiddle with. I love line drivers though. Will never do an install without em.
Kenwood Excelon x592
x200.4(in process of repair OMFG YES)
rsd65cs front
rsd65cs rear
x1200.1
2 rsdc124
using zx350 until repair of x200.4