I was just going to chime in here. It really depends on how you are generating the signal for low/high biamp cables. If you use the "special bi-amp" feature in most processors/receivers, they usually have a circuit that analyzes the actual signal that is played by the "low" part of the biamp. It than uses another circuit to subtract the "used" frequencies from the unused. It then outputs this "unused" signal to the "front high pre-outs" or equivalent. The actual result is a significant loss in resolution and impact. This explains why they sounded very muted and dull. It is not recommended and I honestly don't know why these companies are trying to do this "differential subtraction" circuit because it just destroys the sound quality. They really should have just output the normal "full range" signal on both low/high biamp outputs because the speaker would naturally play only what it needs to (based on internal speaker crossover).
It's probably best just to use a splitter cable, since you have the Rotel amp with 20k input impedance. Al is correct in stating that splitting this into a 10k + 10k load will be fine for solid state components. Actually, pro audio components usually have 10k impedances a lot of the time. If you want a really good Y-splitter cable, check this one out (I'm assuming you're using RCA):
Or you can look for the Audioquest Y-splitter cable for about $20 or less, or something in between.