pre-amp and amp hook up

The Prima's gain is notoriously low.

Most probably this is a gain issue. Check your amp input spec's and see what its input sensitivity is. Check your integrated's line stage output gain. If the former is .5 to 1v and the latter is in about 26, it would be a gain mis-match. If your line stage gain is about 12 and the input sensitivity of the amp is 1.5v, its more likely something else (but I don't know what). You can buy fixed in-line attenuators (Rothwell's $60 on line - these will reduce your gain by 10db), variable in line attenuators which are much more expensive and hard to find, or DIY (I'm sure someone with technical expertise would tell you how). Hope that helps a bit....