Bi-Amping 2 Interconnects or Y Cable?

I don't know if there are any high end Y adapters. I would look for something that at least has good RCA's on it with good plating, and tight fitting. Possibly even Monster, but I just looked at some on Google, and look like they may have their "Turbo" male RCA. If it is this type, you have to turn them clockwise while pulling them (male RCA) off, if they're as tight their old ones were. At that short length, it might not make that much difference, just as long as they fit good and snug.

Go to "Audio Advisor". Search..."Y interconnects". I see some by AudioQuest (1 female, 2 male RCAs). $14.95

These Audioquest Y-adapters work well and avoid any extra cabling.

If I understand correctly, you are referring to the possibility of using a pair of 1-rca female to 2-rca male y-adapters at the power amp inputs, and running a single pair of rca cables from there to the preamp. Vs. running a separate pair of rca cables from each power amp to the two sets of output jacks that apparently are provided on the preamp (which I am pretty certain, in the case of your MC-7 and most other preamps that provide two sets of output jacks, are simply wired together inside the rear panel of the preamp, rather than being separately buffered).

If my understanding of the question is correct, the first issue you would face is that most off-the-shelf y-adapters are very short, and might not be long enough to reach between the input jacks of the two amps. And if a custom-made adapter would be necessary to provide enough length, you might as well purchase a second pair of rca cables, it seems to me.

In any event, given that your preamp probably has a low output impedance, and your power amp has a high input impedance, the one possible technical issue I can foresee with either approach would be a slightly increased likelihood of ground loop issues (hum and/or buzz) with the single-cable + y-adapter approach.

FWIW, here are a couple of y-adapters having the correct genders, including the one from Monster that Hifihvn referred to:

http://www.bhphotovideo.com/c/product/469394-REG/Monster_Cable_600450_RCA_Female_to_2.html

http://www.audioadvisor.com/prodinfo.asp?number=TRS3YFMM

Regards,
-- Al

Follow-up to my previous post: Upon further thought, I suspect that you are referring to a passive vertical bi-amp arrangement, so each y-adapter would be connected between two input connectors of a single amp. Given that, the increased possibility of ground loop issues that I mentioned goes away, and the length issue probably does as well. So I see no problem going with y-adapters. And doing that would have the benefit of substantially reducing the amount of cable capacitance loading the preamp output, vs. having two cables, although that probably won't make any difference given a low preamp output impedance.

Regards,
-- Al