In general, +4 db is "pro" level and -10 db is "consumer" level. As a rule of thumb, most balanced TRS outs are +4, and most RCA jacks are -10, although there are exceptions. A standard consumer CD player is usually -10 db out. I have this problem when jacking an outboard mic pre into my KORG PXR4 Pandora, which is looking for -10 db. Fortunately, EB Tech makes a nifty box called LLS2/LLS8 which converts one to the other either way, and has 1/4" "smart jacks" that will accept balanced or unbalanced lines. The LLS2 (line level shifter) is a 2 channel palm sized unit, and LLS8 is an 8 channel 1u rack box. Neither requires any power, and introduce almost no noise. The former is about $50, and the latter more like $240. This allows me to run the pre hot enough to control noise floor problems without clipping the poor little Pandora. It is also a useful item for importing tracks from any garden variety cassette or CD player. Hope this is useful-Richie