while i cannot speak to this particular 5.1 system, i can say with my Z-2300 2.1 system, i like the sub pretty much, but am completely disallusioned with the sats.
with a clean cd source, run through itunes and Volume Logic, they are at 80% (approx) volume, the sats became tinny, and even entered clipping while playing Yes's "And You And I". the sub is acceptable to me, it handles volume loads into the 90% realm with livable (for me) distortion, at low to moderate sound levels, the sub is a little boomy and loose, but that can be eq'd out. overall the sub is clean sounding and powerful, for $83 i am well pleased with it.
overall my solution is to replace the Z-2300 sats with 2.0 M-Audio AV-40 speakers, they have a reference monitor pedigree, are sturdily constructed (around 7 lbs a piece) 4 inch driver and 1 inch tweeter, and the reviews net-wide are off the chain good. for a $132 (on Amazon, $122 on M-Audios website) plus the $83 i spent for the Z-2300 system, i will have (hopefully) a very solid sounding, powerful 2.1 system for under $220. if i had to do it all over again, i would probably have opted for M-Audios BX-10 sub, yes overkill, but can you truly have too good audio?
Mike