How to hook JL F112 sub to both preamp and pre/pro

Mac:

Barry Ober is a technical consultant for JL. Check out his own personal website at soundoctor.com ( a wealth of audio info and white papers). This guy has an uber-impressive resume, he's an audio engineer and has built recording studios. A very knowledgeable dude.

I think he's credible, to say the least.

Srosenberg, assume your preamp had two sets of outputs for L/R? Also, would assume that one has to be careful not to send signals from both preamp and pre/pro simultaneously, LOL. Seriously though, if that was done in error, could it damage the sub?

Bob, from everything I've read, even the better pre/pros cant compete with a good standalone preamp. Now, to be fair, I havent tested this thesis, but the overwhelming opinion in my research of forums (Agon, AVS, etc) says this is so. Also, adding a good preamp for say 2-3k would be a lot cheaper than paying 8-10k or more for a comparably sounding pre/pro like say a Classe CT or even SSP800, or a Theta Casablanca, or even the soon to be released Bryston SP3 or Cary Cinema 12. Also, the best sound is likely to be from the analog inputs that bypass processing in the these units, and that brings me back to my original problem. I will check out that NHT unit, maybe I can find a used one.

Srosenberg, thanks much for the input. I actually did have an email exchange with Barry at JL and he confirmed what you said, its perfectly fine to run both inputs, LFE/RCA out from pre/pro and balanced/XLR out from preamp.
Not surprised your calypso was better, as I have heard great things about that unit, but VERY surprised about the W4S being so good. What gear are you running? Wondering if there is a certain threshold of gear quality above which such distinctions become more pronounced. I'm running B&W N803 as mains (HTM1 ctr and DS7 surrounds), with Sunfire TGA5200 amp ( a very good and underappreciated amp) and a Sunfire TGP5 pre/pro fed by both a modded Denon 3930ci and a Sonos-BelCanto Dac2 combo. Although not heavy high end, would assume its good enough to hear a difference?

Srosenberg, thats a mighty nice system, and certainly more high end than mine by a longshot. As I stated earlier, I wonder if I'll be able to hear as much of a significant difference with preamp changes as you would in your system. Guess the only way to find out is try it! The W4S Dac seems like a real giant killer based on your experience, so I may give that a shot at some point. By the way, Classe just came out with the CP-800 a killer preamp/dac/async USB all-in-one unit that also has sub-out. $6k pricetag, but thats pretty reasonable for everything it does (as long as it sounds good of course)

Bob, OK, so you are firmly in the camp of processed sound, if done right, sounding better. I'm ok with that (I think Kal at Stereophile agrees with you too). Of course I cant agree or disagree as I've not compared it much, but assume you have and to your ears processed is better? Clearly there are two distinct camps on this, and as always, only your own ears will tell you what you like. Some people firmly believe that room correction is the only way to hear music properly. However, I think the argument on pre/pro vs preamp assumes a certain level (pun?) playing field and, given such, a preamp provides a better, cleaner, clearer picture than does an average pre/pro. Again, assumption on my part from reading forums. No doubt that, in a poor room, processing/correction can probably make a bigger difference and provide better SQ than a good preamp.

[From the description, it seems that Jeff's original idea of a line level switch box would be a simple solution. Decware's box comes to mind]

No, actually, according to Barry, just connect the two units directly to the sub: pre/pro LFE out via RCA to sub, and preamp L/R out via XLR to sub. Just dont send signals out from both units simultaneously!