hi...i have primaluna prologue 6 monoblocks, and primaluna pro 3 preamp, why one of the monoblock seem that lose power compared with the other one?? i already check the tubes, by swapping tubes between monos, but still produce the same result, i check the fuse...it still ok. i listened closely to the speaker that powered by that amp....it still producing sound but im very low volume. what is the problem?? is the output tranformer faulty?? really appreciate if anyone can help me, thx