Ruing an AudioControl DQX and it is a soid unit. I also have a 6xs in my other car and it is doing an excellent job as well. I like both of these units because in addition to their x-over abilities, they both have very good line drivers built in so I can step up the signal at the processor and keep my gains pretty low.
I also have zero noise in my cars. Not sure if this is mostly due to the processors or my RCA's (Stinger Experts), but it all comes together with no engine noises, pops, or whines.
Used to have an MTX RT-X03 and a US Amps US-X3 along with various trunk mounted EQ's, but going to the DQX gives me the fully adjustable 3-way x-over along with plenty of eq bands with a line driver all in one unit. The US Amps unit was very nice in it's own right and is an excellent performer as a line driver and x-over. If it had eq capabilities, I'd still have it.