Who uses long interconnect like in dealers?

Ideal setup has front end components close to listening chair and run long interconnect between pre and power where power amp sits in between speakers; I have seen many high end dealers to adopt this setup and result is usually more than great. This way front end components do not obstruct speaker imaging and can also avoid bass heavy (vibration) location. But if that is ideal, why do I rarely see long interconnect for sale in used market? I don't think people only upgrade components and short interconnects?
I do. Two 6 meter pairs from preamp to amp. Good question (your 2nd to last one). I have one 6 meter pair of Discovery Signature IC if you are interested.
My source equipment is on a side wall and my amps are between the speakers. My IC's to the amps are 4m and my speaker cables are 1m and 1.25m (system is bi-amped).

I have also noticed that there are very few long IC's on the used market. Maybe people don't do this much because the initial cost is so high. Good IC's can cost $1K or more, and I'm not talking about the really expensive stuff. I would love to buy some Audience or AZ 4m cable but just can't quite get there with the finances.

So I'll just continue to watch for that rare used pair to come along and hope someone else doesn't beat me to them.

Good listening.
On your second to last question, perhaps the answer is it's too expensive to upgrade? I use a 40 foot run between my preamp and power amps/active crossover, and that has always been the last thing that would get upgraded because of the cost. I've tried to make that as good a cable as I could, given the limited choices available for that long a run, to avoid having to change it. And it's also possible, I suppose, to send the long run to the manufacturer to reterminate in shorter runs, then sell those, which would be an easier sell in the used market.
I've been using a 6m length of Kimber PBJ (original cost $150) for several years in order to get the source equipment away from the speakers. I am about to change to a 5m length of Kimber Hero (cost $500 w/WBT 0108's) and expect an improvement in sound without significant cost. I've looked for some Hero on the used market for a while but haven't seen anything longer than 3m, so I'm buying new (got to keep up the relationship with the local dealer!). The next step up in the Kimber line is a BIG jump in price (> $1000) so this is where I stop! The important thing when going with long interconnects is making sure the electrical properties don't lead to signal loss over long runs. The Kimber interconnects are very good in this repsect since they are not shielded (and no I have not had problems with interference). I would check with your preamp and amp manufacturer to get their recommended maximum inductance and capacitance values for the interconnect. You'll then have to get the data for the interconnect and do a little math. Kimber has this on their website, others might too. Hope this helps!
I use a 5 meter to one set of amps and a 7 meter run to another set for exactly the reason you suggest, that I'm able i isolate my equipment from standing waves and vibrations which would effect my source components if i located them near the amps/speakers. I'm also able to make adjustments from very close to the listening position. If your preamps can drive long runs of cable its a great way to go. I think the reason you don't see more of this is both ergonomics (i.e. WAF) and cost. You usually have to special order these lenghts and may not get return priveleges - so you really have to do some homework before you commit.
I use an asymmetrical run of 3m + 6m Red Dawn XLR between my rack-mounted Aleph P and the Aleph 2 monos suspended from my basement ceiling joists in milk cartons, with 8' SPM cables up through the baseboards to the Parsifals.
Sounds superb, and has GREAT spousal approval!

For my recording adjunct I run 30' balanced cheap Canare StarQuad pro cables from Earthworks omnis through a Grace Class A pre velcroed under my Steinway to my Alesis in the rack. Completely noisefree, neutral, and detailed. Amazing quality for $0.34/ft!

So here's the big cognitive dissonance: between Alesis Masterlink and the Aleph P pre do I use 1/2 meter of more Canare (ala smart PRO recording), or do I get audiophoolish and think that I need more RD or SPM for the last link?!
What a hobby.
I typically look for VERY long runs of interconnects and cut them down / reterminate them myself. Since most people aren't using long runs of interconnects, the market for great lengths just isn't there and the seller ends up taking a bath when they finally do sell. I've purchased 8 meter runs of Kimber PBJ for $75 for the pair. I also purchased a pair of 10 meter Goertz Copper Micro Purl's for $175. My most recent find was a 10 meter pair of cables that retail for over $2000. I paid $200 delivered.

With some high quality solder, the connectors of my choice and a little time and labor, i've been able to assemble mass quantities of interconnects for pennies on the dollar. After assembling them, i burn all of them in and try them out in my various systems, share them with my Brother and / or Dad, set up systems for friends, etc... This offers unbeatable bang for the buck in my experience.

When shopping for "DIY" based bargains like this, i always try to keep in mind "versatility". Both the PBJ's and Micro-Purl's can easily be configured for use with RCA's ( single ended ) or with XLR's ( balanced ) due to their conductor configuration. As such, what might be a "decent" cable in single ended form can become an even better cable when run in balanced mode. That is, so long as one is willing to get their hands dirty in return for saving a LOT of money.

With that in mind, i hope that a lot of you folks are interested in trying out long interconnects. I'll be waiting when you post them for sale : ) Sean
I use 6m of canare. My installer who installs million dollar theatre setups swore buy these. So I let him run the from my monos to my rack. He had a spool and made them himself on the spot. No problems great sound. canare.com
I tried this a while back. First, put my source/pre on the wall level with my lstening seat with amps by speakers. Noticed an improvement in soundstaging (esp lateral spread) getting the equipment rack out from between the speakers (BTW, some recommend a rack between speakers for anchoring center image, ie, Michael Green).
Then went all out with an 8m Discovery Plus 4 and put all source equipment in closet ( sounded and looked good, but too much hassle).
Now using only one amp and a CD w/ volume control (Resolution CD-55) on low modular racks (Lovan) that don't obstruct image. This way, using <1m ICs allow me to use a better IC (8m Quattro-fil would break my bank). Speakers are way out into the room away from equipment anyway and equipment is somewhat isolated with Aurios/Daruma/Bright Star.
I think a lot is decided by your choice of IC. Some are reasonably inexpensive (?) to increasing lengths (Discovery, Transparent, Purist, etc) and others will cost you a fortune. Dealers can absorb the cost easier than we can (consumers).
I too am looking into this for my set-up. But I'm plagued by the thought of effectivly having this HUGE antenna between my control unit and amp. Yikes! Since I cannot go balanced with my equipment choices, won't this degrade sonic quality? Or are single ended cables shielded enough to stop the pick up?

Mprime, You do have to be careful with cable selection to avoid RFI but unless you have unusual problem in your area good shielded cable should work fine. I would recommend that you audition the cable first. The only problem I have had is when I ran the cables parallel to power cords or near large power supplies - and thats easy to correct. I've never experienced RFI thru the cables.
I use 6 meters of Randall Research TX, which I recently
convert to balanced/XLR.

You rarely see long interconnects because of the wide spread use of equipment racks. I can't believe people continue to put these racks between their speakers.
Kana, how would you describe the sonic differences between the balanced run against the unbalanced?
Mprime- the noise floor was lowered, and output from the preamp increased,which lowered volume settings. Both of which improved low level listening pleasure.

Since the cables had been used for 15 years, there wasn't
any change in the basic sound qualities of the cables.

A nice improvement for $20. in parts and a little bit of

I never had an RF problem in my room with the cables in SE
config, but I think that's more a function of good cable and
equipment design than the length of the cables.

Suggest you borrow a long IC run, and see if it improve the sound of your system. I've run my audio systems with
long ICs and short speaker cables for the last 20 years.
I remember when preamps (all tube) had cathode-follower output stages with 600 ohm impedance. In such a circuit the coax connection to the power amp was critical. At the very least, hum pickup was a problem. Now, if you have a solid state preamp your output impedance is 10 to 50 ohms, and you can transmit that low-level signal a long long way: in particular, much further than you should try to drive the high-current speaker signal. Cheaper too if you buy the coax wire directly from the manufacturer, before it gets the absurd markup that goes with the designation "audiophile".

I run coax from the convenient eye-level shelves in an alcove where the source equipment resides, down to the cellar (that's 6 feet already) and along the cellar ceiling to shelves just under the living room floor where the power amps are located. Probably 30 feet in all. The speaker wires are just long enough to go up through the floor. I have never sensed any problem with this setup, and it sure cost less than the six! (L,Ctr,R, all biamped) 30 foot heavy gauge speaker wires that would otherwise be needed.
The run between my tube preamp and tube amps are kept short. Only 38 feet, and single ended ;^ ).

Most visitors comment that my tonal balance, resolution and high frequency extension is extraordinary. I don't think the length of interconnect is the only factor. The brand and quality of the interconnect along with equipment choice is equally important in determining whether long or short runs produce the best results.
I have a 7 meter IC between pre and amp.