How to hook up a subwoofer with an integrated amp?


I am quite happy with my current 2-channel system, but given that it's driven by a tube integrated (EL34) amp, I have been thinking of adding a good quality subwoofer to enhance the bass department. The question is: how do I hook up a subwoofer with an integrated amp since it doesn't have a sub-out?

Should I:

(1) use Y adapters for each channel to split the signal from the cdp to both the sub and the amp? (cross over concern? degradation of signal to the amp?)
(2) long interconnect to go from cdp to sub's pre-in, then pre-out to the int. amp? (using sub's cross-over, but not prefer due to long I/C's)
(3) Speaker wire from amp to sub, then sub to speakers? (any cross-over concern? degradation of signal to the speakers?)
(4) Any other ideas?

While we are at it, what would be a good quality sub (hopefully under $1,200 used) that goes well with my system:

VAC Avatar Tube Int. Amp
Sonus Faber Grand Piano
Cary 303/100 Cdp
Nordost Blue Heaven Bi-wire spr/IC

All input would be greatly appreciated. Thanks guys!
stevenkc
I would suggest running Y instead of speaker cables.
Since most preamps out there with 2 sets of output which the design just basically "Y" inside the chassis anyways, I don't think Y-ing the line level signal will accfect the sound as mush as Y-ing the speaker cable signal.
Sorry about the mistake with the Cary. I read a review of the 303/200, and it seemed to have a volume control.

In this case, I would prefer using the parallel speaker wire to the sub. If you use a splitter placed at the output of the Cary (or the input of the Avatar), you have no control over the volume presented to the sub. With unity gain, the sub is likely to be too loud, out of balance with the volume of the Sonus Fabers. With a parallel speaker wire configuration, the Avatar's volume control would work for both the speakers and the sub. (The sub should have a volume control intended to match the sub's volume with the main speakers' volume for first time setup use.)

With respect to the crossover, many subs have a crossover control, so that the sub will operate at frequencies where the main speakers are unable to perform. If your Grand Piano's give up below, say, 30 Herz, then the sub should be set to operate below 30 Herz only. In practice, speaker and sub frequency responses tend to slope off, not start or stop in cliffs at specific frequencies, and there will be an overlap, so you might want to adjust the setting so the overall effect of the combined speakers and sub is smooth.

Some subs have a phase control, too. This is used to manage any cancellation or reinforcement of the speakers and the sub where they overlap. For example, if the sub is out of phase with the speakers, it will tend to cancel out the speakers' output for the frequencies where they overlap. If they are in phase, there will be reinforcement. Personally, I prefer to set the phase so there is reinforcement, then I lower the sub's crossover frequency to reduce the overlap until the output is as smooth as possible. Good luck.
Your best bet may be a REL sub. The preferred hookup method for these subs is their supplied low-level cable, which runs from the amp's speaker posts to the sub's Neutrik connector. I used a REL sub with my Lectron integrated (also a 30 watt EL34 amp) and ProAc 1SC's to great effect.
Seth,

Yes. After much reading, I'm currently leaning towards a REL. Question on the Neutrik conector: how long is that cable? I also read about the ground wire. Where do you connect that? Lastly, which REL do you have? I'm thinking either the Strata or the Storm, but have no idea which one would match better with my system. Then there is also the original vs. II vs. III. i.e. should I get a Stata III or a Storm for similar price?!?