Balanced or not for interconnect

Other than the added expense, and all other things being equal, balanced is better.

I like balanced because of hum cancellation and the 6db increase in volume.

IME, I would not sweat a 3M run of single-ended (rca) cables. If I had over a 5M run, I would probably try and use balanced cables. However, as Elizabeth states, it really does depend on the driving capability of your preamp, as well as on the susceptibility of your location to RFI. Use shielded rca cables and don't worry about it if the result sounds good. OTOH, if your gear is all fully balanced, then balanced cables are a no-brainer. I have fully balanced monoblocks, which only have balanced inputs, but my best sound has come from using single-ended preamps. Jensen makes input transformers that you can put just in front of your amps to convert single-ended to balanced and, in my system, they work great with no noticable sonic penalty.

Recently I did a comparison between rca and xlr Nordost Frey ic's in my system. If I 'squinted' or really listened carefully I noticed a slightly better sound stage with the xlr's. That being said that wasn't enough to make my decision to buy them. Instead I bought the rca's because the gain was higher than I cared for. To clarify with the xlr's my max volume was approx 9:30 where with the rca's I can go to approx 11:00 for the same loudness. My cables are 1 meter.