At the risk of hijacking this thread into Rel, I will try to clarify my question... I thought the beauty of Rel's connection was to have both the sub and the mains to take on same sonic character by hooking up to the last of the signal chain - the amplifier. So, regardless of the "quality" of the amp, connecting to a Rotel would provide Rel with Rotel sound while the mains are taking on the sonics of Krell. In the end, it probably won't matter, but at least on theoretical grounds, it may be different.
For example, if you did the same but used MC2301 instead of Rotel, you would have Rel taking on the bass sonic quality of MC2301 which may be different than what Krell 400e may provide. And that difference may be more pronounced as the Rel crossover is increased to higher level. Just a thought
As an audiophile, we do worry about specs a lot - like pico vs femtoseconds of jitter. May not even make an audible difference, but still fun to talk about.