Well, there's no obvious Insert Loop on the 388's Stereo Buss so the compressor is In-line between the 388's Stereo Outs (RCA jacks) and the Yamaha's Rec In jacks. So, if I'm going to read the levels anywhere it'd be at the Yamaha end surely(!?). The 388's stereo meters stay pretty much between -3 and 0 dbs, with only the occasional excursion above 0 (during the choruses and when I double the lead vocal on alternating lines of each verse) so long as I keep all the faders between 4 and 5. But, even at this modest level, and with compression, the Yamaha's meters are still going far into the red. Which leads us to which conclusion?