Learned this week that ground loop is possible even among two surge protectors. With all studio components plugged into two daisy-chained strips, thought everything would be OK. It wasn't. During a mix down, noticed some background hiss and hum. This led to inserting Blue Cat's FreqAnalyst to investigate the problem. (the CM version from Computer Music Magazine.) Shut down equipment one-by-one and observed the relative noise spectrum. Several bumps were predominant in the 60Hz and multiples thereof.

Found that just having the ground pin of one of the KRK studio monitors was enough to introduce a spike in the the hum levels. Heard the term "ground loop" but never really knew what it meant. After investigating the term in wikipedia, did some further research and found some interesting products that can help with power cleanliness. In particular, Blue Circle's BC86 and any of the Monster Power products in the Pro Power line for musicians.

Being creative, tried a number of plug configurations, starting with just the computer and working up to having all 7 plugs connected successfully introducing only minimal hum. The best configuration found was the mixer and powered studio monitors plugged into a separate strip. All other components are plugged into a Monster PowerCenter HT700 power strip for now. Both power strips are now plugged in parallel to the same outlet.

Upgrading to a Monster Pro 2500 this week, so will compare the relative noise floor.