Cables from amp to preamp or longer speaker cables…

I ran a pair of 7.5 meter, unbalanced interconnects from preamp to amps, with very short speaker cables, for years with no problems.  Recently, I replaced my 30-year-old interconnects with Morrow Audio cables, which are unshielded.  This caused some noise problems--my amps hummed more than usual and turning on or off a lamp made noise in the adjacent speaker.  So Morrow will be sending me a specially-made shielded version of the 8-meter interconnects, and hopefully that will solve the problem while still retaining the superb transparency of those cables.

With shielded interconnects, running unbalanced is unlikely to be a problem in an ordinary domestic setup.  In a professional setup where hundreds of feet of cable may be required, balanced cables are appropriate.  If ordinary mic cables can be used for a balanced setup, that could save $$, as long as both amp and preamp have the balanced jacks.  Balanced cables can transmit a higher output, therefore lower perceived noise level than long runs of unbalanced cable.

My speakers are in front of a bare wall and my gear is off to the side. Speakers are bi-wired with long runs of Kimber (I think) 6TC and 8Tc (but that was a long time ago, so I am not positive) and interconnects are 1.5 m of balanced Kimber Silver Streak (I went with 1.5 m because once upon a time I needed more flexibility with gear position).

I personally think my system is sounding fantastic at the present, but this thread has got me rethinking what the sonic advantages might be if I put the amp (Cary V12) on the floor between speakers with short cables and hooked amp to pre with long balanced interconnects. I would need a much longer power cable to do that, however.

Speaker cable you can run for several meters without any noticeable sound difference if they are designed right, no need to cost much either.

+1 au_lait        

I ran these with 30K active speakers they sound terrific!  For the money, unbeatable.  And you can order custom lengths.  Bets of luck.

Since you have a lot of Benchmark gear in your system, you may want to check out the Benchmark website and look at their balanced interconnects. They use a Canare starquad cable and charge $144 for a pair of 25-foot cables. You might be able to find more expensive ICs that sound better in your system - but you might not. This could be a good route to go if you're trying not to spend too much money on long ICs.