Long distance between preamp and power amp

I considered replacing my amplifier, but since I love it so much (it's a Line Magnetic 219ia) and this situation will be temporary for 3 or 4 years (because then I will move again), I prefer to keep the amplifier and work out a solution around the cabling. 

I use 6-meter RCAs (AQ King Cobra) between my preamp in my listening room and my phono preamp in the next room, with no issues.

Rule #1 for single ended cable is to not use them for longer runs (I think rule #2 is don't eat them). Sqlsavior is a rebel rule breaker...

6 meters is not a very long run for an excellent RCA cable. Not a problem. I can speak of older Purist Dominus with full certainty.

There’s no reason to consider selling such a fine amp. If it proves to be necessary you could connect a suitably chosen Jensen transformer (ca. $275) between the preamp and the amp (close to the amp), to convert balanced to unbalanced. That would provide essentially all of the benefits of a balanced connection.

But it may very well not be necessary. What is the make and model of the preamp?

The approach that is best may very possibly depend on several different characteristics of the preamp. Including its output impedance; how its balanced outputs are generated (and therefore whether the sonics of its balanced outputs are likely to be better than, worse than, or similar to the sonics of its unbalanced outputs); and its internal grounding configuration (that may affect susceptibility to ground loop issues, which can be brought out by long lengths of unbalanced cables).

Regards,
-- Al