Connecting a subwoofer.....

What is the difference between using pre-out (if your amp has one) and using line level outputs when hooking up a sub in a two channel system for music only?I know there are a lot of "do's" and "dont's" when connecting a sub and it all has me a bit confused. For instance, I just read someone recommending using a "Y" splitter for the cables and Simaudio told me this morning that if I were to attempt this it would definitely damage the amp.

Yes, I am familiar with that but I am not aware of other subs with Hi Level out. The REL seems to me the only ones I can use with a Naim Nait 5i that has no pre-out. To hook other subs up to this amp isn't possible apparently because of the lack of pre-out.


I just mentioned the "Y" splitter as an example of possibly damaging something by messing around with this and not knowing what I am doing.That is, I don't want to make any other mistakes and regret it due to trial and error.
The question was basically asking is there any benefit/disadvantages from using either line level or pre-out when hooking up a sub that doesn't have high level outs.
Thomas, does your sub have "speaker in" and "speaker out" binding posts? If so, you can just connect speaker cables from the same binding posts you hook your speakers to on the Naim Nait... to the "speaker in" (don't worry about "speaker out") and that way have high level connection like you would with a REL.
The sub can be connected using a rca cable from the amp/recvr sub out which would be line level...or run speaker cables to the sub as if they were the main spkrs...and then more spkr cable from sub to spkrs themselves. That would be speaker level. There is no right or wrong way but rather an ideal way based on your ability or there lack of to control the xover freq. Your amp may or may not have xover freq control...chances are it does not if it's a stereo amp therefor you will want to engage/turn on the subs xover switch and use dial to blend mains with the sub. Say you are using some monitors that are capable of 55-60hz lowend...set sub xover at or about that freq so it takes over where the monitors ign off so that there is a smooth transition. I think this is what you are inquiring...I think.
Thanks a lot so far guys. I was starting to think that maybe I couldn't use a sub with my set-up. Problem is, I have my gear in another country where I am going. If I had it here I am sure I could figure it out. I just want to make sure I have the right/enough cables to bring with me since I have to have a sub with my music. Anyway, due to your help things are looking promising - thanks again.