Subwoofer connection

I'm planning on adding a sub to my two channel system. I don't want to use the sub's crossover actively - feeding it with the standard pre-out outputs from my preamp and then return from the sub to my power - amp since this will require two pairs of long interconnect cables. I'm happy with the high quality short interconnects I now use between the preamp and power amp. So my intention is to simply feed the sub a dulicate of what the amps is getting - which brings me to my questions...

I can buy two Y-adapters to split each pre-out for each channel, feeding the sup with one leg and the amp with the other for each channel. But the Y-adapters will compromise the qualtiy of the high quality interconnects I use between the preamp and the power amp... won't it?

So my thought is to use a single y-adapter between the left and right tape outputs from the preamp and feed the sub with a single cable. My question is whether or not this will have any negative audible or operational impact. I could just use a pair of cables from the tape out to the sub, but if there is no problem using the Y-adapter I would prefer a single cable, since the sub will be quite a distance from the rest of my gear.

RLW