y cables, are they dangerous

what would happen if i used a set of y cables to install another amp into my preamp, both amps would be 8 ohms but different power ratings.

ive seen this done before but im still worried about doing it in my rig as mine costs alot more than the 1 that i saw it done with.

im not makin a move here till im 100% sure that im not gonna fry some caps or somthing even worse.

if you are doing this or have done this please tell me the application you used.

I take it that you only have one set of pre outs, ie some pre amps have both single ended and XLR's outputs. So presuming you only have one I personaly would not do it simply because I would not want to compromise the output going to Amp #1, by dividing the signal with a Y adapter.
As to whether they are dangerous, I would say they are most dangerous to the sound qualiy of your first amp. As to whether it would short out a pre or amp, I doubt it, but I cannot commit to 100 percent assurance.
transporter, i still have a xlr output available but didnt know if the signal would overlap or cancel out the rca connection in the other amp.

my preamp has 3 rca amplifier outputs which are all being used.

im currently biamping a pair of klipschorns with a mcintosh mc 7104 ss amp on bottom & mc2102 tube amp on top & this takes 2 of my outputs.

the 3rd output is running a mcintosh mc300 ss amp powering mcintosh xrt22 speakers & i want to biamp them also with another mc2102 tube amp for the tweeter colums.

my preamp has 1 xlr output that isnt being used,do you think this is the route to take as opposed to the rca's.

im smitten with the results of biamping the khorns & very much want to use another mc2102 on the tweeter colums of the big mac's as the benifits were so obvious.

Honestly Im not sure in this particular application. One issue is will the XLR and RCA outs work simultaneously, my guess would be yes. But the stumbling block is that XLR outputs almost always are at a approx 4db higher output, and this issue would have to be addressed. Lets see what the other Agoners have to say.
Bigjoe, do you have an electronic crossover, or does the tweeter panel have a crossover built-in? You can damage tweeters by running a full-range signal into them without a crossover. At the very least it won't sound good, even if they're not damaged.

Generally, for biamping, the setup would be preamp to electronic crossover, then the crossover would drive each power amp. You wouldn't need a Y adapter.
wow, the plot thickens,luckily the khorns were allready set up for biamping when i got them,at this point im gonna contact roger russel( xrt22 designer ) & see what route he suggests.

it depends..... alot depends on the output stage of the pre and whether it can swing the voltage and impedence. i checked with the designer of pse if i could use a xlr splitter to biamp 4 monoblocs ( i have a pse hl-1 pre with 1 set of xlr outs ).

wether you can use xlr and rca together will depend on if the xlr stage is a true differential design and totally seperate from the rca stage.

if the xlr is wired off the rca ( psuedo balance like the arc ls 2b) then you cant use the xlr and rca together due to the phase shift.

hope that helps,